diff --git a/build/Makefile.in b/build/Makefile.in
index d1cc3a5f5ac..98dabea6a77 100644
--- a/build/Makefile.in
+++ b/build/Makefile.in
@@ -109,6 +109,12 @@ else
 AUTOMATION_PPARGS += -DIS_TEST_BUILD=0
 endif
 
+ifeq ($(MOZ_DEBUG), 1)
+AUTOMATION_PPARGS += -DIS_DEBUG_BUILD=1
+else
+AUTOMATION_PPARGS += -DIS_DEBUG_BUILD=0
+endif
+
 _LEAKTEST_DIR = $(DEPTH)/_leaktest
 
 _LEAKTEST_FILES =    \
diff --git a/build/pgo/Makefile.in b/build/pgo/Makefile.in
index fca787c2a3c..cf00bd156c7 100644
--- a/build/pgo/Makefile.in
+++ b/build/pgo/Makefile.in
@@ -114,6 +114,12 @@ else
 AUTOMATION_PPARGS += -DIS_TEST_BUILD=0
 endif
 
+ifeq ($(MOZ_DEBUG), 1)
+AUTOMATION_PPARGS += -DIS_DEBUG_BUILD=1
+else
+AUTOMATION_PPARGS += -DIS_DEBUG_BUILD=0
+endif
+
 automation.py: automation.py.in
 	$(PYTHON) $(topsrcdir)/config/Preprocessor.py \
 	$(AUTOMATION_PPARGS) $(DEFINES) $(ACDEFINES) $^ > $@
diff --git a/build/pgo/automation.py.in b/build/pgo/automation.py.in
index c054fd051d4..6b9f1ec9d8f 100644
--- a/build/pgo/automation.py.in
+++ b/build/pgo/automation.py.in
@@ -84,6 +84,7 @@ UNIXISH = not IS_WIN32 and not IS_MAC
 #expand DEFAULT_APP = "./" + __BROWSER_PATH__
 #expand CERTS_DIR = __CERTS_DIR__
 #expand IS_TEST_BUILD = __IS_TEST_BUILD__
+#expand IS_DEBUG_BUILD = __IS_DEBUG_BUILD__
 
 ###########
 # LOGGING #
@@ -314,6 +315,13 @@ user_pref("camino.warn_when_closing", false); // Camino-only, harmless to others
 """
   prefs.append(part)
 
+  # Increase the max script run time 10-fold for debug builds
+  if (IS_DEBUG_BUILD):
+    prefs.append("""\
+user_pref("dom.max_script_run_time", 100);
+user_pref("dom.max_chrome_script_run_time", 200);
+""")
+
   locations = readLocations()
 
   # Grant God-power to all the privileged servers on which tests run.
diff --git a/dom/src/base/nsJSEnvironment.cpp b/dom/src/base/nsJSEnvironment.cpp
index 4b46e0752c6..78eedbddc9f 100644
--- a/dom/src/base/nsJSEnvironment.cpp
+++ b/dom/src/base/nsJSEnvironment.cpp
@@ -850,9 +850,6 @@ PrintWinCodebase(nsGlobalWindow *win)
 }
 #endif
 
-// The accumulated operation weight before we call MaybeGC
-const PRUint32 MAYBE_GC_OPERATION_WEIGHT = 5000 * JS_OPERATION_WEIGHT_BASE;
-
 static void
 MaybeGC(JSContext *cx)
 {
@@ -932,24 +929,24 @@ nsJSContext::DOMOperationCallback(JSContext *cx)
 
         if (nsContentUtils::GetBoolPref("dom.prevent_oom_dialog", PR_FALSE))
           return JS_FALSE;
-        
+
         nsCOMPtr<nsIPrompt> prompt = GetPromptFromContext(ctx);
-        
+
         nsXPIDLString title, msg;
         rv = nsContentUtils::GetLocalizedString(nsContentUtils::eDOM_PROPERTIES,
                                                 "LowMemoryTitle",
                                                 title);
-        
+
         rv |= nsContentUtils::GetLocalizedString(nsContentUtils::eDOM_PROPERTIES,
                                                  "LowMemoryMessage",
                                                  msg);
-        
+
         //GetStringFromName can return NS_OK and still give NULL string
         if (NS_FAILED(rv) || !title || !msg) {
           NS_ERROR("Failed to get localized strings.");
           return JS_FALSE;
         }
-        
+
         prompt->Alert(title, msg);
         return JS_FALSE;
       }
@@ -1236,9 +1233,8 @@ nsJSContext::nsJSContext(JSRuntime *aRuntime) : mGCOnDestruction(PR_TRUE)
     nsContentUtils::RegisterPrefCallback(js_options_dot_str,
                                          JSOptionChangedCallback,
                                          this);
-
-    ::JS_SetOperationCallback(mContext, DOMOperationCallback,
-                              MAYBE_GC_OPERATION_WEIGHT);
+    ::JS_SetOperationCallback(mContext, DOMOperationCallback);
+    nsContentUtils::XPConnect()->SetWatchdogLimit(mContext, PR_TicksPerSecond()/10);
 
     static JSLocaleCallbacks localeCallbacks =
       {
diff --git a/dom/src/threads/nsDOMThreadService.cpp b/dom/src/threads/nsDOMThreadService.cpp
index b9519d463eb..25ef7b2b556 100644
--- a/dom/src/threads/nsDOMThreadService.cpp
+++ b/dom/src/threads/nsDOMThreadService.cpp
@@ -733,8 +733,8 @@ nsDOMThreadService::CreateJSContext()
 
   JS_SetErrorReporter(cx, DOMWorkerErrorReporter);
 
-  JS_SetOperationCallback(cx, DOMWorkerOperationCallback,
-                          100 * JS_OPERATION_WEIGHT_BASE);
+  JS_SetOperationCallback(cx, DOMWorkerOperationCallback);
+  nsContentUtils::XPConnect()->SetWatchdogLimit(cx, PR_TicksPerSecond()/100);
 
   static JSSecurityCallbacks securityCallbacks = {
     nsDOMWorkerSecurityManager::JSCheckAccess,
diff --git a/js/src/js.cpp b/js/src/js.cpp
index 9ffc84796a3..674c140fb6a 100644
--- a/js/src/js.cpp
+++ b/js/src/js.cpp
@@ -104,8 +104,9 @@ static size_t gMaxStackSize = 500000;
 static jsuword gStackBase;
 
 static size_t gScriptStackQuota = JS_DEFAULT_SCRIPT_STACK_QUOTA;
-
+#if JS_HAS_OPERATION_COUNT
 static JSBool gEnableBranchCallback = JS_FALSE;
+#endif
 static uint32 gBranchCount;
 static uint32 gBranchLimit;
 
@@ -117,6 +118,18 @@ FILE *gOutFile = NULL;
 static JSBool reportWarnings = JS_TRUE;
 static JSBool compileOnly = JS_FALSE;
 
+#if !JS_HAS_OPERATION_COUNT
+/*
+ * Variables to support watchdog thread.
+ */
+static PRLock *gWatchdogLock;
+static PRCondVar *gWatchdogWakeup;
+static PRBool gWatchdogRunning;
+static PRThread *gWatchdogThread;
+static PRIntervalTime gCurrentInterval;
+static PRIntervalTime gWatchdogLimit;
+#endif
+
 typedef enum JSShellErrNum {
 #define MSG_DEF(name, number, count, exception, format) \
     name = number,
@@ -169,6 +182,7 @@ GetLine(JSContext *cx, char *bufp, FILE *file, const char *prompt) {
     return JS_TRUE;
 }
 
+#if JS_HAS_OPERATION_COUNT
 static JSBool
 my_BranchCallback(JSContext *cx, JSScript *script)
 {
@@ -197,6 +211,132 @@ my_BranchCallback(JSContext *cx, JSScript *script)
 #endif
     return JS_TRUE;
 }
+#endif
+
+#if !JS_HAS_OPERATION_COUNT
+static void
+ShutdownWatchdog()
+{
+    PRThread *t;
+
+    PR_Lock(gWatchdogLock);
+    gWatchdogRunning = PR_FALSE;
+    t = gWatchdogThread;
+    gWatchdogThread = NULL;
+    PR_NotifyCondVar(gWatchdogWakeup);
+    PR_Unlock(gWatchdogLock);
+    if (t)
+        PR_JoinThread(t);
+}
+
+static void
+WakeupWatchdog()
+{
+    PR_Lock(gWatchdogLock);
+    if (gWatchdogThread && gWatchdogLimit &&
+        (gCurrentInterval == PR_INTERVAL_NO_TIMEOUT ||
+         gCurrentInterval > gWatchdogLimit)) {
+        PR_NotifyCondVar(gWatchdogWakeup);
+    }
+    PR_Unlock(gWatchdogLock);
+
+}
+
+static JSBool
+ShellOperationCallback(JSContext *cx)
+{
+    if (gWatchdogLimit) {
+        fprintf(stderr, "Error: Script is running too long\n");
+        return JS_FALSE;
+    }
+    return JS_TRUE;
+}
+
+static void
+WatchdogMain(void *arg)
+{
+    JSRuntime *rt = (JSRuntime *) arg;
+    PRStatus status;
+    PRBool isRunning;
+
+    do {
+        JSContext *iter = NULL;
+        JSContext *acx;
+        JSBool isContextRunning = JS_FALSE;
+        PRIntervalTime ct = PR_IntervalNow();
+
+        PR_Lock(gWatchdogLock);
+        if (gWatchdogLimit) {
+            JS_LOCK_GC(rt);
+            while ((acx = js_ContextIterator(rt, JS_FALSE, &iter))) {
+                if (acx->requestDepth) {
+                    if (ct - acx->startTime > gWatchdogLimit)
+                        JS_TriggerOperationCallback(acx);
+                    if (!isContextRunning)
+                        isContextRunning = JS_TRUE;
+                }
+            }
+            JS_UNLOCK_GC(rt);
+        }
+        gCurrentInterval = (isContextRunning && gWatchdogLimit)
+                           ? gWatchdogLimit
+                           : PR_INTERVAL_NO_TIMEOUT;
+        if (gWatchdogRunning)
+            status = PR_WaitCondVar(gWatchdogWakeup, gCurrentInterval);
+        isRunning = gWatchdogRunning;
+        PR_Unlock(gWatchdogLock);
+    } while (isRunning && status == PR_SUCCESS);
+}
+
+/*
+ * Get the watchdog limit associated with the watchdog callback.
+ */
+static PRIntervalTime
+GetWatchdogLimit(JSContext *cx)
+{
+    return gWatchdogLimit;
+}
+
+/*
+ * Change the watchdog limit associated with the watchdog callback. This API
+ * function may be called only when the result of JS_GetOperationCallback(cx)
+ * is not null.
+ */
+static JSBool
+SetWatchdogLimit(JSContext *cx, PRIntervalTime newWatchdogLimit)
+{
+    if (newWatchdogLimit == gWatchdogLimit)
+        return JS_TRUE;
+
+    gWatchdogLimit = newWatchdogLimit;
+
+    /*
+     * Start a new watchdog thread if it has not been started. If it has been
+     * started wake up the thread and cause the watchdog rescheduling.
+     */
+    PR_Lock(gWatchdogLock);
+    if (!gWatchdogThread) {
+        gWatchdogRunning = PR_TRUE;
+        gWatchdogThread =
+            PR_CreateThread(PRThreadType(PR_USER_THREAD),
+                            WatchdogMain,
+                            cx->runtime,
+                            PRThreadPriority(PR_PRIORITY_NORMAL),
+                            PRThreadScope(PR_LOCAL_THREAD),
+                            PRThreadState(PR_JOINABLE_THREAD),
+                            0);
+    }
+    PR_Unlock(gWatchdogLock);
+    if (!gWatchdogThread) {
+        JS_ReportError(cx, "Failed to create watchdog thread");
+        return JS_FALSE;
+    }
+
+    WakeupWatchdog();
+    return JS_TRUE;
+}
+
+#endif
 
 static void
 SetContextOptions(JSContext *cx)
@@ -217,10 +357,12 @@ SetContextOptions(JSContext *cx)
     }
     JS_SetThreadStackLimit(cx, stackLimit);
     JS_SetScriptStackQuota(cx, gScriptStackQuota);
+#if JS_HAS_OPERATION_COUNT
     if (gEnableBranchCallback) {
         JS_SetBranchCallback(cx, my_BranchCallback);
         JS_ToggleOptions(cx, JSOPTION_NATIVE_BRANCH_CALLBACK);
     }
+#endif
 }
 
 static void
@@ -380,7 +522,9 @@ ProcessArgs(JSContext *cx, JSObject *obj, char **argv, int argc)
             break;
         }
         switch (argv[i][1]) {
+#if JS_HAS_OPERATION_COUNT
           case 'b':
+#endif
           case 'c':
           case 'f':
           case 'e':
@@ -471,7 +615,7 @@ extern void js_InitJITStatsClass(JSContext *cx, JSObject *glob);
                             &jitstats_class, NULL, 0);
 #endif
             break;
-            
+
         case 'o':
             if (++i == argc)
                 return usage();
@@ -501,10 +645,12 @@ extern void js_InitJITStatsClass(JSContext *cx, JSObject *glob);
             }
             break;
 
+#if JS_HAS_OPERATION_COUNT
         case 'b':
             gBranchLimit = atoi(argv[++i]);
             gEnableBranchCallback = (gBranchLimit != 0);
             break;
+#endif
 
         case 'c':
             /* set stack chunk size */
@@ -1451,7 +1597,7 @@ DisassFile(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
     JSScript *script;
     JSBool ok;
     uint32 oldopts;
-    
+
     if (!argc)
         return JS_TRUE;
 
@@ -1471,7 +1617,7 @@ DisassFile(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
     obj = JS_NewScriptObject(cx, script);
     if (!obj)
         return JS_FALSE;
-    
+
     *rval = OBJECT_TO_JSVAL(obj); /* I like to root it, root it. */
     ok = Disassemble(cx, obj, 1, rval, rval); /* gross, but works! */
     *rval = JSVAL_VOID;
@@ -2124,6 +2270,38 @@ ThrowError(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
     return JS_FALSE;
 }
 
+#if !JS_HAS_OPERATION_COUNT
+
+static JSBool
+WatchdogInterval(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
+{
+    if (argc > 1) {
+        JS_ReportError(cx, "Wrong number of arguments");
+        return JS_FALSE;
+    }
+
+    if (argc == 0)
+        return JS_NewDoubleValue(cx, GetWatchdogLimit(cx), rval);
+
+    jsdouble interval;
+    if (!JS_ValueToNumber(cx, argv[0], &interval))
+        return JS_FALSE;
+
+    /* NB: The next condition take negative values and NaNs into account. */
+    if (!(interval >= 0.0)) {
+        JS_ReportError(cx, "Negative or NaN argument value");
+        return JS_FALSE;
+    }
+    if (interval > 1800.0) {
+        JS_ReportError(cx, "Excessive argument value");
+        return JS_FALSE;
+    }
+
+    return SetWatchdogLimit(cx, (PRIntervalTime) (interval * PR_TicksPerSecond()));
+}
+
+#endif
+
 #define LAZY_STANDARD_CLASSES
 
 /* A class for easily testing the inner/outer object callbacks. */
@@ -2684,12 +2862,14 @@ Scatter(JSContext *cx, uintN argc, jsval *vp)
     JSBool ok;
     jsrefcount rc;
 
+#if JS_HAS_OPERATION_COUNT
     if (!gEnableBranchCallback) {
         /* Enable the branch callback, for periodic scope-sharing. */
         gEnableBranchCallback = JS_TRUE;
         JS_SetBranchCallback(cx, my_BranchCallback);
         JS_ToggleOptions(cx, JSOPTION_NATIVE_BRANCH_CALLBACK);
     }
+#endif
 
     sd.lock = NULL;
     sd.cvar = NULL;
@@ -2865,6 +3045,9 @@ static JSFunctionSpec shell_functions[] = {
     JS_FS("stringsAreUTF8", StringsAreUTF8, 0,0,0),
     JS_FS("testUTF8",       TestUTF8,       1,0,0),
     JS_FS("throwError",     ThrowError,     0,0,0),
+#if !JS_HAS_OPERATION_COUNT
+    JS_FS("watchint",       WatchdogInterval,     1,0,0),
+#endif
 #ifdef DEBUG
     JS_FS("dis",            Disassemble,    1,0,0),
     JS_FS("disfile",        DisassFile,     1,0,0),
@@ -2946,6 +3129,11 @@ static const char *const shell_help_messages[] = {
 "stringsAreUTF8()         Check if strings are UTF-8 encoded",
 "testUTF8(mode)           Perform UTF-8 tests (modes are 1 to 4)",
 "throwError()             Throw an error from JS_ReportError",
+#if !JS_HAS_OPERATION_COUNT
+"watchint(interval)       Set watchdog interval to the specified number"
+" of seconds. If parameters are not specified it returns watchdog interval"
+" in seconds",
+#endif
 #ifdef DEBUG
 "dis([fun])               Disassemble functions into bytecodes",
 "disfile('foo.js')        Disassemble script file into bytecodes",
@@ -3887,7 +4075,14 @@ ContextCallback(JSContext *cx, uintN contextOp)
         JS_SetErrorReporter(cx, my_ErrorReporter);
         JS_SetVersion(cx, JSVERSION_LATEST);
         SetContextOptions(cx);
+#if !JS_HAS_OPERATION_COUNT
+        JS_SetOperationCallback(cx, ShellOperationCallback);
+    } else if (contextOp == JSCONTEXT_REQUEST_START &&
+               cx->runtime->state != JSRTS_LANDING) {
+        WakeupWatchdog();
+#endif
     }
+
     return JS_TRUE;
 }
 
@@ -3934,6 +4129,18 @@ main(int argc, char **argv, char **envp)
     rt = JS_NewRuntime(64L * 1024L * 1024L);
     if (!rt)
         return 1;
+
+#if !JS_HAS_OPERATION_COUNT
+    gWatchdogLock = JS_NEW_LOCK();
+    if (!gWatchdogLock)
+        return 1;
+    gWatchdogWakeup = JS_NEW_CONDVAR(gWatchdogLock);
+    if (!gWatchdogWakeup)
+        return 1;
+    gWatchdogLimit = 0;
+    gWatchdogThread = NULL;
+#endif
+
     JS_SetContextCallback(rt, ContextCallback);
 
     cx = JS_NewContext(rt, gStackChunkSize);
@@ -4043,8 +4250,20 @@ main(int argc, char **argv, char **envp)
     JS_EndRequest(cx);
 #endif
 
+#if !JS_HAS_OPERATION_COUNT
+    ShutdownWatchdog();
+#endif
+
+#if !JS_HAS_OPERATION_COUNT
+    if (gWatchdogWakeup)
+        JS_DESTROY_CONDVAR(gWatchdogWakeup);
+    if (gWatchdogLock)
+        JS_DESTROY_LOCK(gWatchdogLock);
+#endif
+
     JS_DestroyContext(cx);
     JS_DestroyRuntime(rt);
     JS_ShutDown();
+
     return result;
 }
diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index db713c82629..4341e63835d 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -903,6 +903,7 @@ JS_BeginRequest(JSContext *cx)
 {
 #ifdef JS_THREADSAFE
     JSRuntime *rt;
+    JSContextCallback cxCallback;
 
     JS_ASSERT(cx->thread->id == js_CurrentThreadId());
     if (!cx->requestDepth) {
@@ -910,6 +911,9 @@ JS_BeginRequest(JSContext *cx)
 
         /* Wait until the GC is finished. */
         rt = cx->runtime;
+#if !JS_HAS_OPERATION_COUNT
+        cx->startTime = PR_IntervalNow();
+#endif
         JS_LOCK_GC(rt);
 
         /* NB: we use cx->thread here, not js_GetCurrentThread(). */
@@ -923,6 +927,16 @@ JS_BeginRequest(JSContext *cx)
         cx->requestDepth = 1;
         cx->outstandingRequests++;
         JS_UNLOCK_GC(rt);
+
+        cxCallback = cx->runtime->cxCallback;
+        if (cxCallback) {
+#ifdef DEBUG
+            JSBool callbackStatus =
+#endif
+                cxCallback(cx, JSCONTEXT_REQUEST_START);
+            JS_ASSERT(callbackStatus);
+        }
+
         return;
     }
     cx->requestDepth++;
@@ -983,7 +997,9 @@ JS_EndRequest(JSContext *cx)
         rt->requestCount--;
         if (rt->requestCount == 0)
             JS_NOTIFY_REQUEST_DONE(rt);
-
+#if !JS_HAS_OPERATION_COUNT
+        cx->startTime = 0;
+#endif
         JS_UNLOCK_GC(rt);
         return;
     }
@@ -3130,7 +3146,7 @@ DefinePropertyById(JSContext *cx, JSObject *obj, jsid id, jsval value,
                                        attrs, flags, tinyid, NULL);
     }
     return OBJ_DEFINE_PROPERTY(cx, obj, id, value, getter, setter, attrs,
-                               NULL);   
+                               NULL);
 }
 
 static JSBool
@@ -3807,7 +3823,7 @@ JS_HasUCProperty(JSContext *cx, JSObject *obj,
     JSProperty *prop;
 
     CHECK_REQUEST(cx);
-    ok = LookupUCProperty(cx, obj, name, namelen, 
+    ok = LookupUCProperty(cx, obj, name, namelen,
                           JSRESOLVE_QUALIFIED | JSRESOLVE_DETECTING,
                           &obj2, &prop);
     if (ok) {
@@ -5244,6 +5260,7 @@ JS_CallFunctionValue(JSContext *cx, JSObject *obj, jsval fval, uintN argc,
     return ok;
 }
 
+#if JS_HAS_OPERATION_COUNT
 JS_PUBLIC_API(void)
 JS_SetOperationCallback(JSContext *cx, JSOperationCallback callback,
                         uint32 operationLimit)
@@ -5319,6 +5336,33 @@ JS_SetBranchCallback(JSContext *cx, JSBranchCallback cb)
     }
     return oldcb;
 }
+#else
+
+JS_PUBLIC_API(void)
+JS_SetOperationCallback(JSContext *cx, JSOperationCallback callback)
+{
+    cx->operationCallback = callback;
+}
+
+JS_PUBLIC_API(void)
+JS_ClearOperationCallback(JSContext *cx)
+{
+    cx->operationCallback = NULL;
+}
+
+JS_PUBLIC_API(JSOperationCallback)
+JS_GetOperationCallback(JSContext *cx)
+{
+    return cx->operationCallback;
+}
+
+#endif
+
+JS_PUBLIC_API(void)
+JS_TriggerOperationCallback(JSContext *cx)
+{
+    cx->operationCount = 0;
+}
 
 JS_PUBLIC_API(JSBool)
 JS_IsRunning(JSContext *cx)
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 78421929151..db250c80537 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -45,6 +45,7 @@
  */
 #include <stddef.h>
 #include <stdio.h>
+#include "jsversion.h"
 #include "js-config.h"
 #include "jspubtd.h"
 #include "jsutil.h"
@@ -2166,6 +2167,13 @@ extern JS_PUBLIC_API(JSBool)
 JS_CallFunctionValue(JSContext *cx, JSObject *obj, jsval fval, uintN argc,
                      jsval *argv, jsval *rval);
 
+extern JS_PUBLIC_API(void)
+JS_ClearOperationCallback(JSContext *cx);
+
+extern JS_PUBLIC_API(JSOperationCallback)
+JS_GetOperationCallback(JSContext *cx);
+
+#if JS_HAS_OPERATION_COUNT
 /*
  * The maximum value of the operation limit to pass to JS_SetOperationCallback
  * and JS_SetOperationLimit.
@@ -2190,12 +2198,6 @@ extern JS_PUBLIC_API(void)
 JS_SetOperationCallback(JSContext *cx, JSOperationCallback callback,
                         uint32 operationLimit);
 
-extern JS_PUBLIC_API(void)
-JS_ClearOperationCallback(JSContext *cx);
-
-extern JS_PUBLIC_API(JSOperationCallback)
-JS_GetOperationCallback(JSContext *cx);
-
 /*
  * Get the operation limit associated with the operation callback. This API
  * function may be called only when the result of JS_GetOperationCallback(cx)
@@ -2223,6 +2225,18 @@ JS_SetOperationLimit(JSContext *cx, uint32 operationLimit);
  */
 extern JS_PUBLIC_API(JSBranchCallback)
 JS_SetBranchCallback(JSContext *cx, JSBranchCallback cb);
+#else
+/*
+ * Set the operation callback that the engine calls while resetting
+ * context.
+ */
+extern JS_PUBLIC_API(void)
+JS_SetOperationCallback(JSContext *cx, JSOperationCallback callback);
+
+#endif
+
+extern JS_PUBLIC_API(void)
+JS_TriggerOperationCallback(JSContext *cx);
 
 extern JS_PUBLIC_API(JSBool)
 JS_IsRunning(JSContext *cx);
diff --git a/js/src/jscntxt.cpp b/js/src/jscntxt.cpp
index c06a334cb6f..70dddb69111 100644
--- a/js/src/jscntxt.cpp
+++ b/js/src/jscntxt.cpp
@@ -241,7 +241,11 @@ js_NewContext(JSRuntime *rt, size_t stackChunkSize)
     memset(cx, 0, sizeof *cx);
 
     cx->runtime = rt;
+#if JS_OPERATION_COUNT
     JS_ClearOperationCallback(cx);
+#else
+    cx->operationCount = 1;
+#endif
     cx->debugHooks = &rt->globalDebugHooks;
 #if JS_STACK_GROWTH_DIRECTION > 0
     cx->stackLimit = (jsuword)-1;
@@ -516,7 +520,7 @@ js_ValidContextPointer(JSRuntime *rt, JSContext *cx)
     return JS_FALSE;
 }
 
-JSContext *
+JS_FRIEND_API(JSContext *)
 js_ContextIterator(JSRuntime *rt, JSBool unlocked, JSContext **iterp)
 {
     JSContext *cx = *iterp;
@@ -1371,9 +1375,11 @@ js_GetErrorMessage(void *userRef, const char *locale, const uintN errorNumber)
 JSBool
 js_ResetOperationCount(JSContext *cx)
 {
+    JS_ASSERT(cx->operationCount <= 0);
+
+#if JS_HAS_OPERATION_COUNT
     JSScript *script;
 
-    JS_ASSERT(cx->operationCount <= 0);
     JS_ASSERT(cx->operationLimit > 0);
 
     cx->operationCount = (int32) cx->operationLimit;
@@ -1390,5 +1396,13 @@ js_ResetOperationCount(JSContext *cx)
         if (script || JS_HAS_OPTION(cx, JSOPTION_NATIVE_BRANCH_CALLBACK))
             return ((JSBranchCallback) cx->operationCallback)(cx, script);
     }
+#else
+    JSOperationCallback operationCallback;
+
+    cx->operationCount = 1;
+    operationCallback = cx->operationCallback;
+    if (operationCallback)
+        return operationCallback(cx);
+#endif
     return JS_TRUE;
 }
diff --git a/js/src/jscntxt.h b/js/src/jscntxt.h
index c201f1f8823..07a965050cc 100644
--- a/js/src/jscntxt.h
+++ b/js/src/jscntxt.h
@@ -739,7 +739,11 @@ struct JSContext {
      * Operation count. It is declared early in the structure as a frequently
      * accessed field.
      */
+#if !JS_HAS_OPERATION_COUNT
+    volatile int32      operationCount;
+#else
     int32               operationCount;
+#endif
 
 #if JS_HAS_XML_SUPPORT
     /*
@@ -848,8 +852,10 @@ struct JSContext {
      * but operationCallback is not null, operationCallback stores the branch
      * callback.
      */
+#if JS_HAS_OPERATION_COUNT
     uint32              operationCallbackIsSet :    1;
     uint32              operationLimit         :    31;
+#endif
     JSOperationCallback operationCallback;
 
     /* Interpreter activation count. */
@@ -875,6 +881,10 @@ struct JSContext {
     ((JSContext *)((char *)(tl) - offsetof(JSContext, threadLinks)))
 #endif
 
+#if !JS_HAS_OPERATION_COUNT
+    PRIntervalTime      startTime;          /* time when the context thread was started */
+#endif
+
     /* PDL of stack headers describing stack slots not rooted by argv, etc. */
     JSStackHeader       *stackHeaders;
 
@@ -1038,7 +1048,7 @@ js_ValidContextPointer(JSRuntime *rt, JSContext *cx);
  * If unlocked, acquire and release rt->gcLock around *iterp update; otherwise
  * the caller must be holding rt->gcLock.
  */
-extern JSContext *
+extern JS_FRIEND_API(JSContext *)
 js_ContextIterator(JSRuntime *rt, JSBool unlocked, JSContext **iterp);
 
 /*
@@ -1200,9 +1210,11 @@ extern JSErrorFormatString js_ErrorFormatString[JSErr_Limit];
  * This macro can run the full GC. Return true if it is OK to continue and
  * false otherwise.
  */
-#define JS_CHECK_OPERATION_LIMIT(cx, weight)                                  \
+#if JS_HAS_OPERATION_COUNT
+
+# define JS_CHECK_OPERATION_LIMIT(cx, weight)                                 \
     (JS_CHECK_OPERATION_WEIGHT(weight),                                       \
-     (((cx)->operationCount -= (weight)) > 0 || js_ResetOperationCount(cx)))
+    (((cx)->operationCount -= (weight)) > 0 || js_ResetOperationCount(cx)))
 
 /*
  * A version of JS_CHECK_OPERATION_LIMIT that just updates the operation count
@@ -1210,31 +1222,35 @@ extern JSErrorFormatString js_ErrorFormatString[JSErr_Limit];
  * the count to 0 when it becomes negative to prevent a wrap-around when the
  * macro is called repeatably.
  */
-#define JS_COUNT_OPERATION(cx, weight)                                        \
+# define JS_COUNT_OPERATION(cx, weight)                                       \
     ((void)(JS_CHECK_OPERATION_WEIGHT(weight),                                \
-            (cx)->operationCount = ((cx)->operationCount > 0)                 \
-                                   ? (cx)->operationCount - (weight)          \
-                                   : 0))
+     (cx)->operationCount = ((cx)->operationCount > 0)                        \
+                            ? (cx)->operationCount - (weight)                 \
+                            : 0))
 
 /*
  * The implementation of the above macros assumes that subtracting weights
  * twice from a positive number does not wrap-around INT32_MIN.
  */
-#define JS_CHECK_OPERATION_WEIGHT(weight)                                     \
+# define JS_CHECK_OPERATION_WEIGHT(weight)                                    \
     (JS_ASSERT((uint32) (weight) > 0),                                        \
      JS_ASSERT((uint32) (weight) < JS_BIT(30)))
 
 /* Relative operations weights. */
-#define JSOW_JUMP                   1
-#define JSOW_ALLOCATION             100
-#define JSOW_LOOKUP_PROPERTY        5
-#define JSOW_GET_PROPERTY           10
-#define JSOW_SET_PROPERTY           20
-#define JSOW_NEW_PROPERTY           200
-#define JSOW_DELETE_PROPERTY        30
-#define JSOW_ENTER_SHARP            JS_OPERATION_WEIGHT_BASE
-#define JSOW_SCRIPT_JUMP            JS_OPERATION_WEIGHT_BASE
-
+# define JSOW_JUMP                 1
+# define JSOW_ALLOCATION           100
+# define JSOW_LOOKUP_PROPERTY      5
+# define JSOW_GET_PROPERTY         10
+# define JSOW_SET_PROPERTY         20
+# define JSOW_NEW_PROPERTY         200
+# define JSOW_DELETE_PROPERTY      30
+# define JSOW_ENTER_SHARP          JS_OPERATION_WEIGHT_BASE
+# define JSOW_SCRIPT_JUMP          JS_OPERATION_WEIGHT_BASE
+#else
+# define JS_CHECK_OPERATION_LIMIT(cx, weight)                                 \
+     (((cx)->operationCount) > 0 || js_ResetOperationCount(cx))
+# define JS_COUNT_OPERATION(cx, weight) ((void) 0)
+#endif
 /*
  * Reset the operation count and call the operation callback assuming that the
  * operation limit is reached.
diff --git a/js/src/jsinterp.cpp b/js/src/jsinterp.cpp
index 3131507577e..cece7379f36 100644
--- a/js/src/jsinterp.cpp
+++ b/js/src/jsinterp.cpp
@@ -2665,14 +2665,23 @@ js_Interpret(JSContext *cx)
      * Prepare to call a user-supplied branch handler, and abort the script
      * if it returns false.
      */
-#define CHECK_BRANCH()                                                        \
+#if JS_HAS_OPERATION_COUNT
+# define CHECK_BRANCH()                                                       \
     JS_BEGIN_MACRO                                                            \
         if ((cx->operationCount -= JSOW_SCRIPT_JUMP) <= 0) {                  \
             if (!js_ResetOperationCount(cx))                                  \
                 goto error;                                                   \
         }                                                                     \
     JS_END_MACRO
-
+#else
+# define CHECK_BRANCH()                                                       \
+    JS_BEGIN_MACRO                                                            \
+        if (cx->operationCount < 1) {                                         \
+            if (!js_ResetOperationCount(cx))                                  \
+                goto error;                                                   \
+        }                                                                     \
+    JS_END_MACRO
+#endif
 #define BRANCH(n)                                                             \
     JS_BEGIN_MACRO                                                            \
         regs.pc += n;                                                         \
@@ -5951,7 +5960,7 @@ js_Interpret(JSContext *cx)
             }
 
             TRACE_2(DefLocalFunSetSlot, slot, obj);
-            
+
             fp->slots[slot] = OBJECT_TO_JSVAL(obj);
           END_CASE(JSOP_DEFLOCALFUN)
 
diff --git a/js/src/jspubtd.h b/js/src/jspubtd.h
index 1e3f33aff06..cd67cbd5d1e 100644
--- a/js/src/jspubtd.h
+++ b/js/src/jspubtd.h
@@ -106,8 +106,8 @@ typedef enum JSAccessMode {
     JSACC_PROTO  = 0,           /* XXXbe redundant w.r.t. id */
     JSACC_PARENT = 1,           /* XXXbe redundant w.r.t. id */
 
-                                /* 
-                                 * enum value #2 formerly called JSACC_IMPORT, 
+                                /*
+                                 * enum value #2 formerly called JSACC_IMPORT,
                                  * gap preserved for liveconnect ABI compatibility.
                                  */
 
@@ -594,21 +594,25 @@ typedef JSBool
 
 typedef enum JSContextOp {
     JSCONTEXT_NEW,
-    JSCONTEXT_DESTROY
+    JSCONTEXT_DESTROY,
+    JSCONTEXT_REQUEST_START
 } JSContextOp;
 
 /*
  * The possible values for contextOp when the runtime calls the callback are:
- *   JSCONTEXT_NEW      JS_NewContext successfully created a new JSContext
- *                      instance. The callback can initialize the instance as
- *                      required. If the callback returns false, the instance
- *                      will be destroyed and JS_NewContext returns null. In
- *                      this case the callback is not called again.
- *   JSCONTEXT_DESTROY  One of JS_DestroyContext* methods is called. The
- *                      callback may perform its own cleanup and must always
- *                      return true.
- *   Any other value    For future compatibility the callback must do nothing
- *                      and return true in this case.
+ *  JSCONTEXT_NEW           JS_NewContext successfully created a new JSContext
+ *                          instance. The callback can initialize the instance as
+ *                          required. If the callback returns false, the instance
+ *                          will be destroyed and JS_NewContext returns null. In
+ *                          this case the callback is not called again.
+ *  JSCONTEXT_DESTROY       One of JS_DestroyContext* methods is called. The
+ *                          callback may perform its own cleanup and must always
+ *                          return true.
+ *  JSCONTEXT_REQUEST_START JS_BeginRequest was called with requestDepth == 0.
+ *                          This callback can be used to notify other components
+ *                          that execution has begun on this context.
+ *  Any other value         For future compatibility the callback must do nothing
+ *                          and return true in this case.
  */
 typedef JSBool
 (* JSContextCallback)(JSContext *cx, uintN contextOp);
diff --git a/js/src/jsversion.h b/js/src/jsversion.h
index b16953be814..22268cb9070 100644
--- a/js/src/jsversion.h
+++ b/js/src/jsversion.h
@@ -241,3 +241,11 @@
 
 /* Feature-test macro for evolving destructuring support. */
 #define JS_HAS_DESTRUCTURING_SHORTHAND  (JS_HAS_DESTRUCTURING == 2)
+
+#ifndef JS_HAS_OPERATION_COUNT
+# if defined(MOZILLA_VERSION) || defined(JS_THREADSAFE)
+#  define JS_HAS_OPERATION_COUNT 0
+# else
+#  define JS_HAS_OPERATION_COUNT 1
+# endif
+#endif
diff --git a/js/src/xpconnect/idl/nsIXPConnect.idl b/js/src/xpconnect/idl/nsIXPConnect.idl
index 79eec6c1618..46c039c93ad 100644
--- a/js/src/xpconnect/idl/nsIXPConnect.idl
+++ b/js/src/xpconnect/idl/nsIXPConnect.idl
@@ -70,6 +70,7 @@
 [ptr] native nsScriptObjectTracerPtr(nsScriptObjectTracer);
 [ref] native nsCCTraversalCallbackRef(nsCycleCollectionTraversalCallback);
 [ptr] native nsAXPCNativeCallContextPtr(nsAXPCNativeCallContext);
+      native PRIntervalTime(PRIntervalTime);
 
 /***************************************************************************/
 
@@ -405,7 +406,7 @@ interface nsIXPCFunctionThisTranslator : nsISupports
     { 0xbd, 0xd6, 0x0, 0x0, 0x64, 0x65, 0x73, 0x74 } }
 %}
 
-[uuid(d4c6bc06-2a4f-4315-90ec-d12904aca046)]
+[uuid(eb95710a-e112-44ae-abe1-6f8dfb58d7f8)]
 interface nsIXPConnect : nsISupports
 {
 %{ C++
@@ -767,4 +768,20 @@ interface nsIXPConnect : nsISupports
         in PRUint32 flags,
         in PRUint32 interfaceCount,
         [array, size_is(interfaceCount)] in nsIIDPtr interfaceArray);
+
+    /**
+     * Returns the value of the watchdog limit for the specified context.
+     * @param cx
+     *     A context
+     */
+    [noscript,notxpcom] PRIntervalTime getWatchdogLimit(in JSContextPtr cx);
+
+    /**
+     * Sets a new value of the watchdog limit.
+     * @param cx
+     *     A context
+     * @param limit
+     *     New value of the watchdog limit.
+     */
+    [noscript,notxpcom] PRBool setWatchdogLimit(in JSContextPtr cx, in PRIntervalTime limit);
 };
diff --git a/js/src/xpconnect/src/nsXPConnect.cpp b/js/src/xpconnect/src/nsXPConnect.cpp
index 99997ebc06b..90f733e1430 100644
--- a/js/src/xpconnect/src/nsXPConnect.cpp
+++ b/js/src/xpconnect/src/nsXPConnect.cpp
@@ -319,13 +319,13 @@ static PRBool NameTester(nsIInterfaceInfoManager* manager, const void* data,
            *info;
 }
 
-static nsresult FindInfo(InfoTester tester, const void* data, 
+static nsresult FindInfo(InfoTester tester, const void* data,
                          nsIInterfaceInfoSuperManager* iism,
                          nsIInterfaceInfo** info)
 {
     if(tester(iism, data, info))
         return NS_OK;
-    
+
     // If not found, then let's ask additional managers.
 
     PRBool yes;
@@ -345,9 +345,9 @@ static nsresult FindInfo(InfoTester tester, const void* data,
                 return NS_OK;
         }
     }
-    
+
     return NS_ERROR_NO_INTERFACE;
-}    
+}
 
 nsresult
 nsXPConnect::GetInfoForIID(const nsIID * aIID, nsIInterfaceInfo** info)
@@ -434,7 +434,7 @@ nsXPConnect::Collect()
     // 1. marking of the roots in category 1 by having the JS GC do its marking
     // 2. cycle collection
     // 3. marking of the roots in category 2 by
-    //    XPCJSRuntime::TraceXPConnectRoots 
+    //    XPCJSRuntime::TraceXPConnectRoots
     // 4. sweeping of unmarked JS objects
     //
     // During cycle collection, marked JS objects (and the objects they hold)
@@ -520,7 +520,7 @@ NoteJSRoot(JSTracer *trc, void *thing, uint32 kind)
 }
 #endif
 
-nsresult 
+nsresult
 nsXPConnect::BeginCycleCollection(nsCycleCollectionTraversalCallback &cb)
 {
 #ifdef DEBUG_CC
@@ -588,7 +588,7 @@ nsXPConnect::RecordTraversal(void *p, nsISupports *s)
 }
 #endif
 
-nsresult 
+nsresult
 nsXPConnect::FinishCycleCollection()
 {
 #ifdef DEBUG_CC
@@ -875,7 +875,7 @@ nsXPConnect::Traverse(void *p, nsCycleCollectionTraversalCallback &cb)
 
     if(traceKind != JSTRACE_OBJECT)
         return NS_OK;
-    
+
     JSObject *obj = static_cast<JSObject*>(p);
     JSClass* clazz = OBJ_GET_CLASS(cx, obj);
 
@@ -1205,7 +1205,7 @@ nsXPConnect::WrapNative(JSContext * aJSContext,
     NS_ASSERTION(!XPCNativeWrapper::IsNativeWrapper(returnObj),
                  "Shouldn't be returning a native wrapper here");
 #endif
-    
+
     return NS_OK;
 }
 
@@ -1692,7 +1692,7 @@ nsXPConnect::GetFunctionThisTranslator(const nsIID & aIID,
 }
 
 /* void setSafeJSContextForCurrentThread (in JSContextPtr cx); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPConnect::SetSafeJSContextForCurrentThread(JSContext * cx)
 {
     XPCCallContext ccx(NATIVE_CALLER);
@@ -1713,10 +1713,10 @@ nsXPConnect::ClearAllWrappedNativeSecurityPolicies()
 }
 
 /* void restoreWrappedNativePrototype (in JSContextPtr aJSContext, in JSObjectPtr aScope, in nsIClassInfo aClassInfo, in nsIXPConnectJSObjectHolder aPrototype); */
-NS_IMETHODIMP 
-nsXPConnect::RestoreWrappedNativePrototype(JSContext * aJSContext, 
-                                           JSObject * aScope, 
-                                           nsIClassInfo * aClassInfo, 
+NS_IMETHODIMP
+nsXPConnect::RestoreWrappedNativePrototype(JSContext * aJSContext,
+                                           JSObject * aScope,
+                                           nsIClassInfo * aClassInfo,
                                            nsIXPConnectJSObjectHolder * aPrototype)
 {
     XPCCallContext ccx(NATIVE_CALLER, aJSContext);
@@ -1874,10 +1874,10 @@ nsXPConnect::GetXPCWrappedNativeJSClassInfo(const JSClass **clazz,
 }
 
 /* nsIXPConnectJSObjectHolder getWrappedNativePrototype (in JSContextPtr aJSContext, in JSObjectPtr aScope, in nsIClassInfo aClassInfo); */
-NS_IMETHODIMP 
-nsXPConnect::GetWrappedNativePrototype(JSContext * aJSContext, 
-                                       JSObject * aScope, 
-                                       nsIClassInfo *aClassInfo, 
+NS_IMETHODIMP
+nsXPConnect::GetWrappedNativePrototype(JSContext * aJSContext,
+                                       JSObject * aScope,
+                                       nsIClassInfo *aClassInfo,
                                        nsIXPConnectJSObjectHolder **_retval)
 {
     XPCCallContext ccx(NATIVE_CALLER, aJSContext);
@@ -1893,14 +1893,14 @@ nsXPConnect::GetWrappedNativePrototype(JSContext * aJSContext,
     XPCWrappedNative::GatherProtoScriptableCreateInfo(aClassInfo, &sciProto);
 
     AutoMarkingWrappedNativeProtoPtr proto(ccx);
-    proto = XPCWrappedNativeProto::GetNewOrUsed(ccx, scope, aClassInfo, 
+    proto = XPCWrappedNativeProto::GetNewOrUsed(ccx, scope, aClassInfo,
                                                 &sciProto, JS_FALSE,
                                                 OBJ_IS_NOT_GLOBAL);
     if(!proto)
         return UnexpectedFailure(NS_ERROR_FAILURE);
 
     nsIXPConnectJSObjectHolder* holder;
-    *_retval = holder = XPCJSObjectHolder::newHolder(ccx, 
+    *_retval = holder = XPCJSObjectHolder::newHolder(ccx,
                                                      proto->GetJSProtoObject());
     if(!holder)
         return UnexpectedFailure(NS_ERROR_FAILURE);
@@ -1971,7 +1971,7 @@ nsXPConnect::UpdateXOWs(JSContext* aJSContext,
 }
 
 /* void releaseJSContext (in JSContextPtr aJSContext, in PRBool noGC); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPConnect::ReleaseJSContext(JSContext * aJSContext, PRBool noGC)
 {
     NS_ASSERTION(aJSContext, "bad param");
@@ -1979,8 +1979,8 @@ nsXPConnect::ReleaseJSContext(JSContext * aJSContext, PRBool noGC)
     if(tls)
     {
         XPCCallContext* ccx = nsnull;
-        for(XPCCallContext* cur = tls->GetCallContext(); 
-            cur; 
+        for(XPCCallContext* cur = tls->GetCallContext();
+            cur;
             cur = cur->GetPrevCallContext())
         {
             if(cur->GetJSContext() == aJSContext)
@@ -1989,11 +1989,11 @@ nsXPConnect::ReleaseJSContext(JSContext * aJSContext, PRBool noGC)
                 // Keep looping to find the deepest matching call context.
             }
         }
-    
+
         if(ccx)
         {
 #ifdef DEBUG_xpc_hacker
-            printf("!xpc - deferring destruction of JSContext @ %p\n", 
+            printf("!xpc - deferring destruction of JSContext @ %p\n",
                    (void *)aJSContext);
 #endif
             ccx->SetDestroyJSContextInDestructor(JS_TRUE);
@@ -2002,12 +2002,12 @@ nsXPConnect::ReleaseJSContext(JSContext * aJSContext, PRBool noGC)
         }
         // else continue on and synchronously destroy the JSContext ...
 
-        NS_ASSERTION(!tls->GetJSContextStack() || 
+        NS_ASSERTION(!tls->GetJSContextStack() ||
                      !tls->GetJSContextStack()->
                         DEBUG_StackHasJSContext(aJSContext),
                      "JSContext still in threadjscontextstack!");
     }
-    
+
     if(noGC)
         JS_DestroyContextNoGC(aJSContext);
     else
@@ -2128,7 +2128,7 @@ nsXPConnect::DebugDumpEvalInJSStackFrame(PRUint32 aFrameNumber, const char *aSou
 }
 
 /* JSVal variantToJS (in JSContextPtr ctx, in JSObjectPtr scope, in nsIVariant value); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPConnect::VariantToJS(JSContext* ctx, JSObject* scope, nsIVariant* value, jsval* _retval)
 {
     NS_PRECONDITION(ctx, "bad param");
@@ -2143,7 +2143,7 @@ nsXPConnect::VariantToJS(JSContext* ctx, JSObject* scope, nsIVariant* value, jsv
     nsresult rv = NS_OK;
     if(!XPCVariant::VariantDataToJS(ccx, value, scope, &rv, _retval))
     {
-        if(NS_FAILED(rv)) 
+        if(NS_FAILED(rv))
             return rv;
 
         return NS_ERROR_FAILURE;
@@ -2153,7 +2153,7 @@ nsXPConnect::VariantToJS(JSContext* ctx, JSObject* scope, nsIVariant* value, jsv
 }
 
 /* nsIVariant JSToVariant (in JSContextPtr ctx, in JSVal value); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPConnect::JSToVariant(JSContext* ctx, jsval value, nsIVariant** _retval)
 {
     NS_PRECONDITION(ctx, "bad param");
@@ -2165,7 +2165,7 @@ nsXPConnect::JSToVariant(JSContext* ctx, jsval value, nsIVariant** _retval)
         return NS_ERROR_FAILURE;
 
     *_retval = XPCVariant::newVariant(ccx, value);
-    if(!(*_retval)) 
+    if(!(*_retval))
         return NS_ERROR_FAILURE;
 
     return NS_OK;
@@ -2173,7 +2173,7 @@ nsXPConnect::JSToVariant(JSContext* ctx, jsval value, nsIVariant** _retval)
 
 /* void flagSystemFilenamePrefix (in string filenamePrefix,
  *                                in PRBool aWantNativeWrappers); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPConnect::FlagSystemFilenamePrefix(const char *aFilenamePrefix,
                                       PRBool aWantNativeWrappers)
 {
@@ -2376,6 +2376,18 @@ nsXPConnect::SetSafeJSContext(JSContext * aSafeJSContext)
     return data->GetJSContextStack()->SetSafeJSContext(aSafeJSContext);
 }
 
+NS_IMETHODIMP_(PRBool)
+nsXPConnect::SetWatchdogLimit(JSContext *cx, PRIntervalTime limit)
+{
+    return GetRuntime()->SetWatchdogLimit(cx, limit);
+}
+
+NS_IMETHODIMP_(PRIntervalTime)
+nsXPConnect::GetWatchdogLimit(JSContext *cx)
+{
+    return GetRuntime()->GetWatchdogLimit(cx);
+}
+
 /* These are here to be callable from a debugger */
 JS_BEGIN_EXTERN_C
 JS_EXPORT_API(void) DumpJSStack()
diff --git a/js/src/xpconnect/src/xpccomponents.cpp b/js/src/xpconnect/src/xpccomponents.cpp
index 0e52b66115d..4383d41b875 100644
--- a/js/src/xpconnect/src/xpccomponents.cpp
+++ b/js/src/xpconnect/src/xpccomponents.cpp
@@ -765,7 +765,7 @@ nsXPCComponents_InterfacesByID::CanSetProperty(const nsIID * iid, const PRUnicha
 
 
 
-class nsXPCComponents_Classes : 
+class nsXPCComponents_Classes :
   public nsIXPCComponents_Classes,
   public nsIXPCScriptable,
   public nsIClassInfo
@@ -783,9 +783,9 @@ public:
 };
 
 /***************************************************************************/
-/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval] 
+/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval]
                        out nsIIDPtr array); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Classes::GetInterfaces(PRUint32 *aCount, nsIID * **aArray)
 {
     PRUint32 count = 2;
@@ -818,8 +818,8 @@ oom:
 }
 
 /* nsISupports getHelperForLanguage (in PRUint32 language); */
-NS_IMETHODIMP 
-nsXPCComponents_Classes::GetHelperForLanguage(PRUint32 language, 
+NS_IMETHODIMP
+nsXPCComponents_Classes::GetHelperForLanguage(PRUint32 language,
                                       nsISupports **retval)
 {
     *retval = nsnull;
@@ -827,7 +827,7 @@ nsXPCComponents_Classes::GetHelperForLanguage(PRUint32 language,
 }
 
 /* readonly attribute string contractID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Classes::GetContractID(char * *aContractID)
 {
     *aContractID = nsnull;
@@ -835,7 +835,7 @@ nsXPCComponents_Classes::GetContractID(char * *aContractID)
 }
 
 /* readonly attribute string classDescription; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Classes::GetClassDescription(char * *aClassDescription)
 {
     static const char classDescription[] = "XPCComponents_Classes";
@@ -844,7 +844,7 @@ nsXPCComponents_Classes::GetClassDescription(char * *aClassDescription)
 }
 
 /* readonly attribute nsCIDPtr classID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Classes::GetClassID(nsCID * *aClassID)
 {
     *aClassID = nsnull;
@@ -852,7 +852,7 @@ nsXPCComponents_Classes::GetClassID(nsCID * *aClassID)
 }
 
 /* readonly attribute PRUint32 implementationLanguage; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Classes::GetImplementationLanguage(
     PRUint32 *aImplementationLanguage)
 {
@@ -861,7 +861,7 @@ nsXPCComponents_Classes::GetImplementationLanguage(
 }
 
 /* readonly attribute PRUint32 flags; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Classes::GetFlags(PRUint32 *aFlags)
 {
     *aFlags = nsIClassInfo::THREADSAFE;
@@ -869,7 +869,7 @@ nsXPCComponents_Classes::GetFlags(PRUint32 *aFlags)
 }
 
 /* [notxpcom] readonly attribute nsCID classIDNoAlloc; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Classes::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
 {
     return NS_ERROR_NOT_AVAILABLE;
@@ -1038,9 +1038,9 @@ public:
 };
 
 /***************************************************************************/
-/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval] 
+/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval]
                        out nsIIDPtr array); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ClassesByID::GetInterfaces(PRUint32 *aCount, nsIID * **aArray)
 {
     PRUint32 count = 2;
@@ -1073,8 +1073,8 @@ oom:
 }
 
 /* nsISupports getHelperForLanguage (in PRUint32 language); */
-NS_IMETHODIMP 
-nsXPCComponents_ClassesByID::GetHelperForLanguage(PRUint32 language, 
+NS_IMETHODIMP
+nsXPCComponents_ClassesByID::GetHelperForLanguage(PRUint32 language,
                                       nsISupports **retval)
 {
     *retval = nsnull;
@@ -1082,7 +1082,7 @@ nsXPCComponents_ClassesByID::GetHelperForLanguage(PRUint32 language,
 }
 
 /* readonly attribute string contractID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ClassesByID::GetContractID(char * *aContractID)
 {
     *aContractID = nsnull;
@@ -1090,7 +1090,7 @@ nsXPCComponents_ClassesByID::GetContractID(char * *aContractID)
 }
 
 /* readonly attribute string classDescription; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ClassesByID::GetClassDescription(char * *aClassDescription)
 {
     static const char classDescription[] = "XPCComponents_Interfaces";
@@ -1099,7 +1099,7 @@ nsXPCComponents_ClassesByID::GetClassDescription(char * *aClassDescription)
 }
 
 /* readonly attribute nsCIDPtr classID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ClassesByID::GetClassID(nsCID * *aClassID)
 {
     *aClassID = nsnull;
@@ -1107,7 +1107,7 @@ nsXPCComponents_ClassesByID::GetClassID(nsCID * *aClassID)
 }
 
 /* readonly attribute PRUint32 implementationLanguage; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ClassesByID::GetImplementationLanguage(
     PRUint32 *aImplementationLanguage)
 {
@@ -1116,7 +1116,7 @@ nsXPCComponents_ClassesByID::GetImplementationLanguage(
 }
 
 /* readonly attribute PRUint32 flags; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ClassesByID::GetFlags(PRUint32 *aFlags)
 {
     *aFlags = nsIClassInfo::THREADSAFE;
@@ -1124,7 +1124,7 @@ nsXPCComponents_ClassesByID::GetFlags(PRUint32 *aFlags)
 }
 
 /* [notxpcom] readonly attribute nsCID classIDNoAlloc; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ClassesByID::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
 {
     return NS_ERROR_NOT_AVAILABLE;
@@ -1312,9 +1312,9 @@ public:
 };
 
 /***************************************************************************/
-/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval] 
+/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval]
                        out nsIIDPtr array); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Results::GetInterfaces(PRUint32 *aCount, nsIID * **aArray)
 {
     PRUint32 count = 2;
@@ -1347,8 +1347,8 @@ oom:
 }
 
 /* nsISupports getHelperForLanguage (in PRUint32 language); */
-NS_IMETHODIMP 
-nsXPCComponents_Results::GetHelperForLanguage(PRUint32 language, 
+NS_IMETHODIMP
+nsXPCComponents_Results::GetHelperForLanguage(PRUint32 language,
                                       nsISupports **retval)
 {
     *retval = nsnull;
@@ -1356,7 +1356,7 @@ nsXPCComponents_Results::GetHelperForLanguage(PRUint32 language,
 }
 
 /* readonly attribute string contractID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Results::GetContractID(char * *aContractID)
 {
     *aContractID = nsnull;
@@ -1364,7 +1364,7 @@ nsXPCComponents_Results::GetContractID(char * *aContractID)
 }
 
 /* readonly attribute string classDescription; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Results::GetClassDescription(char * *aClassDescription)
 {
     static const char classDescription[] = "XPCComponents_Interfaces";
@@ -1373,7 +1373,7 @@ nsXPCComponents_Results::GetClassDescription(char * *aClassDescription)
 }
 
 /* readonly attribute nsCIDPtr classID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Results::GetClassID(nsCID * *aClassID)
 {
     *aClassID = nsnull;
@@ -1381,7 +1381,7 @@ nsXPCComponents_Results::GetClassID(nsCID * *aClassID)
 }
 
 /* readonly attribute PRUint32 implementationLanguage; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Results::GetImplementationLanguage(
     PRUint32 *aImplementationLanguage)
 {
@@ -1390,7 +1390,7 @@ nsXPCComponents_Results::GetImplementationLanguage(
 }
 
 /* readonly attribute PRUint32 flags; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Results::GetFlags(PRUint32 *aFlags)
 {
     *aFlags = nsIClassInfo::THREADSAFE;
@@ -1398,7 +1398,7 @@ nsXPCComponents_Results::GetFlags(PRUint32 *aFlags)
 }
 
 /* [notxpcom] readonly attribute nsCID classIDNoAlloc; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Results::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
 {
     return NS_ERROR_NOT_AVAILABLE;
@@ -1544,9 +1544,9 @@ private:
 };
 
 /***************************************************************************/
-/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval] 
+/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval]
                        out nsIIDPtr array); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ID::GetInterfaces(PRUint32 *aCount, nsIID * **aArray)
 {
     PRUint32 count = 2;
@@ -1579,8 +1579,8 @@ oom:
 }
 
 /* nsISupports getHelperForLanguage (in PRUint32 language); */
-NS_IMETHODIMP 
-nsXPCComponents_ID::GetHelperForLanguage(PRUint32 language, 
+NS_IMETHODIMP
+nsXPCComponents_ID::GetHelperForLanguage(PRUint32 language,
                                       nsISupports **retval)
 {
     *retval = nsnull;
@@ -1588,7 +1588,7 @@ nsXPCComponents_ID::GetHelperForLanguage(PRUint32 language,
 }
 
 /* readonly attribute string contractID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ID::GetContractID(char * *aContractID)
 {
     *aContractID = nsnull;
@@ -1596,7 +1596,7 @@ nsXPCComponents_ID::GetContractID(char * *aContractID)
 }
 
 /* readonly attribute string classDescription; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ID::GetClassDescription(char * *aClassDescription)
 {
     static const char classDescription[] = "XPCComponents_Interfaces";
@@ -1605,7 +1605,7 @@ nsXPCComponents_ID::GetClassDescription(char * *aClassDescription)
 }
 
 /* readonly attribute nsCIDPtr classID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ID::GetClassID(nsCID * *aClassID)
 {
     *aClassID = nsnull;
@@ -1613,7 +1613,7 @@ nsXPCComponents_ID::GetClassID(nsCID * *aClassID)
 }
 
 /* readonly attribute PRUint32 implementationLanguage; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ID::GetImplementationLanguage(
     PRUint32 *aImplementationLanguage)
 {
@@ -1622,7 +1622,7 @@ nsXPCComponents_ID::GetImplementationLanguage(
 }
 
 /* readonly attribute PRUint32 flags; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ID::GetFlags(PRUint32 *aFlags)
 {
     *aFlags = nsIClassInfo::THREADSAFE;
@@ -1630,7 +1630,7 @@ nsXPCComponents_ID::GetFlags(PRUint32 *aFlags)
 }
 
 /* [notxpcom] readonly attribute nsCID classIDNoAlloc; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_ID::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
 {
     return NS_ERROR_NOT_AVAILABLE;
@@ -1771,9 +1771,9 @@ private:
 };
 
 /***************************************************************************/
-/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval] 
+/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval]
                        out nsIIDPtr array); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Exception::GetInterfaces(PRUint32 *aCount, nsIID * **aArray)
 {
     PRUint32 count = 2;
@@ -1806,8 +1806,8 @@ oom:
 }
 
 /* nsISupports getHelperForLanguage (in PRUint32 language); */
-NS_IMETHODIMP 
-nsXPCComponents_Exception::GetHelperForLanguage(PRUint32 language, 
+NS_IMETHODIMP
+nsXPCComponents_Exception::GetHelperForLanguage(PRUint32 language,
                                       nsISupports **retval)
 {
     *retval = nsnull;
@@ -1815,7 +1815,7 @@ nsXPCComponents_Exception::GetHelperForLanguage(PRUint32 language,
 }
 
 /* readonly attribute string contractID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Exception::GetContractID(char * *aContractID)
 {
     *aContractID = nsnull;
@@ -1823,7 +1823,7 @@ nsXPCComponents_Exception::GetContractID(char * *aContractID)
 }
 
 /* readonly attribute string classDescription; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Exception::GetClassDescription(char * *aClassDescription)
 {
     static const char classDescription[] = "XPCComponents_Interfaces";
@@ -1832,7 +1832,7 @@ nsXPCComponents_Exception::GetClassDescription(char * *aClassDescription)
 }
 
 /* readonly attribute nsCIDPtr classID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Exception::GetClassID(nsCID * *aClassID)
 {
     *aClassID = nsnull;
@@ -1840,7 +1840,7 @@ nsXPCComponents_Exception::GetClassID(nsCID * *aClassID)
 }
 
 /* readonly attribute PRUint32 implementationLanguage; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Exception::GetImplementationLanguage(
     PRUint32 *aImplementationLanguage)
 {
@@ -1849,7 +1849,7 @@ nsXPCComponents_Exception::GetImplementationLanguage(
 }
 
 /* readonly attribute PRUint32 flags; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Exception::GetFlags(PRUint32 *aFlags)
 {
     *aFlags = nsIClassInfo::THREADSAFE;
@@ -1857,7 +1857,7 @@ nsXPCComponents_Exception::GetFlags(PRUint32 *aFlags)
 }
 
 /* [notxpcom] readonly attribute nsCID classIDNoAlloc; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Exception::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
 {
     return NS_ERROR_NOT_AVAILABLE;
@@ -2064,9 +2064,9 @@ private:
 };
 
 /***************************************************************************/
-/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval] 
+/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval]
                        out nsIIDPtr array); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCConstructor::GetInterfaces(PRUint32 *aCount, nsIID * **aArray)
 {
     PRUint32 count = 2;
@@ -2099,8 +2099,8 @@ oom:
 }
 
 /* nsISupports getHelperForLanguage (in PRUint32 language); */
-NS_IMETHODIMP 
-nsXPCConstructor::GetHelperForLanguage(PRUint32 language, 
+NS_IMETHODIMP
+nsXPCConstructor::GetHelperForLanguage(PRUint32 language,
                                       nsISupports **retval)
 {
     *retval = nsnull;
@@ -2108,7 +2108,7 @@ nsXPCConstructor::GetHelperForLanguage(PRUint32 language,
 }
 
 /* readonly attribute string contractID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCConstructor::GetContractID(char * *aContractID)
 {
     *aContractID = nsnull;
@@ -2116,7 +2116,7 @@ nsXPCConstructor::GetContractID(char * *aContractID)
 }
 
 /* readonly attribute string classDescription; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCConstructor::GetClassDescription(char * *aClassDescription)
 {
     static const char classDescription[] = "XPCComponents_Interfaces";
@@ -2125,7 +2125,7 @@ nsXPCConstructor::GetClassDescription(char * *aClassDescription)
 }
 
 /* readonly attribute nsCIDPtr classID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCConstructor::GetClassID(nsCID * *aClassID)
 {
     *aClassID = nsnull;
@@ -2133,7 +2133,7 @@ nsXPCConstructor::GetClassID(nsCID * *aClassID)
 }
 
 /* readonly attribute PRUint32 implementationLanguage; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCConstructor::GetImplementationLanguage(
     PRUint32 *aImplementationLanguage)
 {
@@ -2142,7 +2142,7 @@ nsXPCConstructor::GetImplementationLanguage(
 }
 
 /* readonly attribute PRUint32 flags; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCConstructor::GetFlags(PRUint32 *aFlags)
 {
     *aFlags = nsIClassInfo::THREADSAFE;
@@ -2150,7 +2150,7 @@ nsXPCConstructor::GetFlags(PRUint32 *aFlags)
 }
 
 /* [notxpcom] readonly attribute nsCID classIDNoAlloc; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCConstructor::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
 {
     return NS_ERROR_NOT_AVAILABLE;
@@ -2329,9 +2329,9 @@ private:
 };
 
 /***************************************************************************/
-/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval] 
+/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval]
                        out nsIIDPtr array); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Constructor::GetInterfaces(PRUint32 *aCount, nsIID * **aArray)
 {
     PRUint32 count = 2;
@@ -2364,8 +2364,8 @@ oom:
 }
 
 /* nsISupports getHelperForLanguage (in PRUint32 language); */
-NS_IMETHODIMP 
-nsXPCComponents_Constructor::GetHelperForLanguage(PRUint32 language, 
+NS_IMETHODIMP
+nsXPCComponents_Constructor::GetHelperForLanguage(PRUint32 language,
                                       nsISupports **retval)
 {
     *retval = nsnull;
@@ -2373,7 +2373,7 @@ nsXPCComponents_Constructor::GetHelperForLanguage(PRUint32 language,
 }
 
 /* readonly attribute string contractID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Constructor::GetContractID(char * *aContractID)
 {
     *aContractID = nsnull;
@@ -2381,7 +2381,7 @@ nsXPCComponents_Constructor::GetContractID(char * *aContractID)
 }
 
 /* readonly attribute string classDescription; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Constructor::GetClassDescription(char * *aClassDescription)
 {
     static const char classDescription[] = "XPCComponents_Interfaces";
@@ -2390,7 +2390,7 @@ nsXPCComponents_Constructor::GetClassDescription(char * *aClassDescription)
 }
 
 /* readonly attribute nsCIDPtr classID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Constructor::GetClassID(nsCID * *aClassID)
 {
     *aClassID = nsnull;
@@ -2398,7 +2398,7 @@ nsXPCComponents_Constructor::GetClassID(nsCID * *aClassID)
 }
 
 /* readonly attribute PRUint32 implementationLanguage; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Constructor::GetImplementationLanguage(
     PRUint32 *aImplementationLanguage)
 {
@@ -2407,7 +2407,7 @@ nsXPCComponents_Constructor::GetImplementationLanguage(
 }
 
 /* readonly attribute PRUint32 flags; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Constructor::GetFlags(PRUint32 *aFlags)
 {
     *aFlags = nsIClassInfo::THREADSAFE;
@@ -2415,7 +2415,7 @@ nsXPCComponents_Constructor::GetFlags(PRUint32 *aFlags)
 }
 
 /* [notxpcom] readonly attribute nsCID classIDNoAlloc; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents_Constructor::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
 {
     return NS_ERROR_NOT_AVAILABLE;
@@ -3220,7 +3220,7 @@ xpc_CreateSandboxObject(JSContext * cx, jsval * vp, nsISupports *prinOrSop)
             if (!principal || NS_FAILED(rv)) {
                 if (NS_SUCCEEDED(rv))
                     rv = NS_ERROR_FAILURE;
-                
+
                 return rv;
             }
         }
@@ -3386,7 +3386,7 @@ public:
 
 private:
     static JSBool ContextHolderOperationCallback(JSContext *cx);
-    
+
     XPCAutoJSContext mJSContext;
     JSContext* mOrigCx;
 };
@@ -3405,11 +3405,17 @@ ContextHolder::ContextHolder(JSContext *aOuterCx, JSObject *aSandbox)
         JS_SetGlobalObject(mJSContext, aSandbox);
         JS_SetContextPrivate(mJSContext, this);
 
-        if(JS_GetOperationCallback(aOuterCx))
+        PRIntervalTime watchdogLimit =
+            nsXPConnect::GetXPConnect()->GetWatchdogLimit(aOuterCx);
+
+        if(watchdogLimit)
         {
-            JS_SetOperationCallback(mJSContext, ContextHolderOperationCallback,
-                                    JS_GetOperationLimit(aOuterCx));
+            JS_SetOperationCallback(mJSContext,
+                                    ContextHolderOperationCallback);
+            nsXPConnect::GetXPConnect()->SetWatchdogLimit(mJSContext,
+                                                          watchdogLimit);
         }
+
     }
 }
 
@@ -3431,7 +3437,9 @@ ContextHolder::ContextHolderOperationCallback(JSContext *cx)
         {
             // If the callback is still set in the original context, reflect
             // a possibly updated operation limit into cx.
-            JS_SetOperationLimit(cx, JS_GetOperationLimit(origCx));
+            PRIntervalTime limit =
+                nsXPConnect::GetXPConnect()->GetWatchdogLimit(origCx);
+            ok = nsXPConnect::GetXPConnect()->SetWatchdogLimit(cx, limit);
             return ok;
         }
     }
@@ -3736,9 +3744,9 @@ NS_INTERFACE_MAP_END_THREADSAFE
 NS_IMPL_THREADSAFE_ADDREF(nsXPCComponents)
 NS_IMPL_THREADSAFE_RELEASE(nsXPCComponents)
 
-/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval] 
+/* void getInterfaces (out PRUint32 count, [array, size_is (count), retval]
                        out nsIIDPtr array); */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents::GetInterfaces(PRUint32 *aCount, nsIID * **aArray)
 {
     PRUint32 count = 2;
@@ -3777,8 +3785,8 @@ oom:
 }
 
 /* nsISupports getHelperForLanguage (in PRUint32 language); */
-NS_IMETHODIMP 
-nsXPCComponents::GetHelperForLanguage(PRUint32 language, 
+NS_IMETHODIMP
+nsXPCComponents::GetHelperForLanguage(PRUint32 language,
                                       nsISupports **retval)
 {
     *retval = nsnull;
@@ -3786,7 +3794,7 @@ nsXPCComponents::GetHelperForLanguage(PRUint32 language,
 }
 
 /* readonly attribute string contractID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents::GetContractID(char * *aContractID)
 {
     *aContractID = nsnull;
@@ -3794,7 +3802,7 @@ nsXPCComponents::GetContractID(char * *aContractID)
 }
 
 /* readonly attribute string classDescription; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents::GetClassDescription(char * *aClassDescription)
 {
     static const char classDescription[] = "XPCComponents";
@@ -3803,7 +3811,7 @@ nsXPCComponents::GetClassDescription(char * *aClassDescription)
 }
 
 /* readonly attribute nsCIDPtr classID; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents::GetClassID(nsCID * *aClassID)
 {
     *aClassID = nsnull;
@@ -3811,7 +3819,7 @@ nsXPCComponents::GetClassID(nsCID * *aClassID)
 }
 
 /* readonly attribute PRUint32 implementationLanguage; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents::GetImplementationLanguage(
     PRUint32 *aImplementationLanguage)
 {
@@ -3820,7 +3828,7 @@ nsXPCComponents::GetImplementationLanguage(
 }
 
 /* readonly attribute PRUint32 flags; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents::GetFlags(PRUint32 *aFlags)
 {
     *aFlags = nsIClassInfo::THREADSAFE;
@@ -3828,7 +3836,7 @@ nsXPCComponents::GetFlags(PRUint32 *aFlags)
 }
 
 /* [notxpcom] readonly attribute nsCID classIDNoAlloc; */
-NS_IMETHODIMP 
+NS_IMETHODIMP
 nsXPCComponents::GetClassIDNoAlloc(nsCID *aClassIDNoAlloc)
 {
     return NS_ERROR_NOT_AVAILABLE;
diff --git a/js/src/xpconnect/src/xpccontext.cpp b/js/src/xpconnect/src/xpccontext.cpp
index f6f95f53414..7d52a68e18f 100644
--- a/js/src/xpconnect/src/xpccontext.cpp
+++ b/js/src/xpconnect/src/xpccontext.cpp
@@ -52,6 +52,7 @@ XPCContext::XPCContext(XPCJSRuntime* aRuntime,
         mPendingResult(NS_OK),
         mSecurityManager(nsnull),
         mException(nsnull),
+        mWatchdogLimit(0),
         mCallingLangType(LANG_UNKNOWN),
         mSecurityManagerFlags(0)
 {
diff --git a/js/src/xpconnect/src/xpcjsruntime.cpp b/js/src/xpconnect/src/xpcjsruntime.cpp
index 6a22af73088..c7e487a7c72 100644
--- a/js/src/xpconnect/src/xpcjsruntime.cpp
+++ b/js/src/xpconnect/src/xpcjsruntime.cpp
@@ -216,7 +216,7 @@ static JSDHashOperator
 DetachedWrappedNativeProtoMarker(JSDHashTable *table, JSDHashEntryHdr *hdr,
                                  uint32 number, void *arg)
 {
-    XPCWrappedNativeProto* proto = 
+    XPCWrappedNativeProto* proto =
         (XPCWrappedNativeProto*)((JSDHashEntryStub*)hdr)->key;
 
     proto->Mark();
@@ -239,6 +239,14 @@ ContextCallback(JSContext *cx, uintN operation)
         {
             delete XPCContext::GetXPCContext(cx);
         }
+        else if(operation == JSCONTEXT_REQUEST_START)
+        {
+            // If we're called during context creation, we will assert if we
+            // try to call XPCContext::GetXPCContext.
+            if(!cx->data2)
+                return JS_TRUE;
+            self->WakeupWatchdog(cx);
+        }
     }
     return JS_TRUE;
 }
@@ -309,7 +317,7 @@ void XPCJSRuntime::TraceJS(JSTracer* trc, void* data)
     // them here.
     for(XPCRootSetElem *e = self->mObjectHolderRoots; e ; e = e->GetNextRoot())
         static_cast<XPCJSObjectHolder*>(e)->TraceJS(trc);
-        
+
     if(self->GetXPConnect()->ShouldTraceRoots())
     {
         // Only trace these if we're not cycle-collecting, the cycle collector
@@ -527,7 +535,7 @@ JSBool XPCJSRuntime::GCCallback(JSContext *cx, JSGCStatus status)
             case JSGC_MARK_END:
             {
                 NS_ASSERTION(!self->mDoingFinalization, "bad state");
-    
+
                 // mThreadRunningGC indicates that GC is running
                 { // scoped lock
                     XPCAutoLock lock(self->GetMapLock());
@@ -550,8 +558,8 @@ JSBool XPCJSRuntime::GCCallback(JSContext *cx, JSGCStatus status)
                         Enumerate(WrappedJSDyingJSObjectFinder, &data);
                 }
 
-                // Do cleanup in NativeInterfaces. This part just finds 
-                // member cloned function objects that are about to be 
+                // Do cleanup in NativeInterfaces. This part just finds
+                // member cloned function objects that are about to be
                 // collected. It does not deal with collection of interfaces or
                 // sets at this point.
                 CX_AND_XPCRT_Data data = {cx, self};
@@ -716,7 +724,7 @@ JSBool XPCJSRuntime::GCCallback(JSContext *cx, JSGCStatus status)
                     if(threadLock)
                     {
                         // Do the marking...
-                        
+
                         { // scoped lock
                             nsAutoLock lock(threadLock);
 
@@ -735,7 +743,7 @@ JSBool XPCJSRuntime::GCCallback(JSContext *cx, JSGCStatus status)
                                     // possibly be valid.
                                     if(ccxp->CanGetTearOff())
                                     {
-                                        XPCWrappedNativeTearOff* to = 
+                                        XPCWrappedNativeTearOff* to =
                                             ccxp->GetTearOff();
                                         if(to)
                                             to->Mark();
@@ -744,7 +752,7 @@ JSBool XPCJSRuntime::GCCallback(JSContext *cx, JSGCStatus status)
                                 }
                             }
                         }
-    
+
                         // Do the sweeping...
                         XPCWrappedNativeScope::SweepAllWrappedNativeTearOffs();
                     }
@@ -820,6 +828,126 @@ JSBool XPCJSRuntime::GCCallback(JSContext *cx, JSGCStatus status)
     return JS_TRUE;
 }
 
+/* static */
+void
+XPCJSRuntime::WatchdogMain(void *arg)
+{
+    XPCJSRuntime *xpcrt = (XPCJSRuntime *) arg;
+    JSRuntime *rt = xpcrt->GetJSRuntime();
+    PRStatus status;
+    PRBool isRunning;
+
+    do
+    {
+        JSContext *iter = NULL;
+        JSContext *acx;
+        PRIntervalTime newInterval = (PRIntervalTime) 0;
+        XPCContext *ccx;
+
+        PRIntervalTime ct = PR_IntervalNow();
+        PR_Lock(xpcrt->mWatchdogLock);
+        JS_LOCK_GC(rt);
+
+        while((acx = js_ContextIterator(rt, JS_FALSE, &iter)))
+        {
+            if(acx->requestDepth)
+            {
+                ccx = XPCContext::GetXPCContext(acx);
+                if(ccx->mWatchdogLimit &&
+                   ct - acx->startTime > ccx->mWatchdogLimit)
+                {
+                    JS_TriggerOperationCallback(acx);
+                }
+                if(newInterval > ccx->mWatchdogLimit || !newInterval)
+                    newInterval = ccx->mWatchdogLimit;
+            }
+        }
+        JS_UNLOCK_GC(rt);
+
+        xpcrt->mCurrentInterval = newInterval ? newInterval
+                                              : PR_INTERVAL_NO_TIMEOUT;
+        if (xpcrt->mWatchdogRunning)
+            status = PR_WaitCondVar(xpcrt->mWatchdogWakeup,
+                                    xpcrt->mCurrentInterval);
+        isRunning = xpcrt->mWatchdogRunning;
+        PR_Unlock(xpcrt->mWatchdogLock);
+    } while (isRunning && status == PR_SUCCESS);
+}
+
+PRBool
+XPCJSRuntime::SetWatchdogLimit(JSContext *cx, PRIntervalTime newWatchdogLimit)
+{
+    PRBool isRunning;
+    PRIntervalTime oldWatchdogLimit;
+    XPCContext *ccx = XPCContext::GetXPCContext(cx);
+
+    if(newWatchdogLimit == ccx->mWatchdogLimit)
+        return PR_TRUE;
+
+    oldWatchdogLimit = ccx->mWatchdogLimit;
+    ccx->mWatchdogLimit = newWatchdogLimit;
+
+    /*
+     * Start a new watchdog thread if it has not been started. If it has been
+     * started wake up the thread and cause the watchdog rescheduling.
+     */
+    PR_Lock(mWatchdogLock);
+    isRunning = !!mWatchdogThread;
+
+    if(!isRunning)
+    {
+        mWatchdogRunning = PR_TRUE;
+        mWatchdogThread =
+            PR_CreateThread(PRThreadType(PR_USER_THREAD),
+                            WatchdogMain,
+                            this,
+                            PRThreadPriority(PR_PRIORITY_NORMAL),
+                            PRThreadScope(PR_LOCAL_THREAD),
+                            PRThreadState(PR_JOINABLE_THREAD),
+                            0);
+    }
+    PR_Unlock(mWatchdogLock);
+    if(!mWatchdogThread)
+        return PR_FALSE;
+    if(isRunning &&
+       (oldWatchdogLimit > ccx->mWatchdogLimit ||
+        mCurrentInterval == PR_INTERVAL_NO_TIMEOUT))
+        WakeupWatchdog(cx);
+    return PR_TRUE;
+
+}
+
+void
+XPCJSRuntime::WakeupWatchdog(JSContext *cx)
+{
+    XPCContext *ccx = XPCContext::GetXPCContext(cx);
+    PR_Lock(mWatchdogLock);
+    if(mCurrentInterval == PR_INTERVAL_NO_TIMEOUT ||
+       (ccx && mCurrentInterval > ccx->mWatchdogLimit))
+        PR_NotifyCondVar(mWatchdogWakeup);
+    PR_Unlock(mWatchdogLock);
+}
+
+PRBool
+XPCJSRuntime::ShutdownWatchdog()
+{
+    PR_Lock(mWatchdogLock);
+    mWatchdogRunning = PR_FALSE;
+    PRThread *t = mWatchdogThread;
+    mWatchdogThread = NULL;
+    PR_NotifyCondVar(mWatchdogWakeup);
+    PR_Unlock(mWatchdogLock);
+    if(t)
+        PR_JoinThread(t);
+    return PR_TRUE;
+}
+
+PRIntervalTime
+XPCJSRuntime::GetWatchdogLimit(JSContext *cx)
+{
+    return XPCContext::GetXPCContext(cx)->mWatchdogLimit;
+}
+
 /***************************************************************************/
 
 #ifdef XPC_CHECK_WRAPPERS_AT_SHUTDOWN
@@ -850,7 +978,7 @@ static JSDHashOperator
 DetachedWrappedNativeProtoShutdownMarker(JSDHashTable *table, JSDHashEntryHdr *hdr,
                                          uint32 number, void *arg)
 {
-    XPCWrappedNativeProto* proto = 
+    XPCWrappedNativeProto* proto =
         (XPCWrappedNativeProto*)((JSDHashEntryStub*)hdr)->key;
 
     proto->SystemIsBeingShutDown((JSContext*)arg);
@@ -1011,6 +1139,12 @@ XPCJSRuntime::~XPCJSRuntime()
         mClearedGlobalObjects.ops = nsnull;
     }
 
+    ShutdownWatchdog();
+    if(mWatchdogWakeup)
+        JS_DESTROY_CONDVAR(mWatchdogWakeup);
+    if(mWatchdogLock)
+        JS_DESTROY_LOCK(mWatchdogLock);
+
     if(mJSRuntime)
     {
         JS_DestroyRuntime(mJSRuntime);
@@ -1098,6 +1232,11 @@ XPCJSRuntime::XPCJSRuntime(nsXPConnect* aXPConnect)
     if(mJSRuntime && !JS_GetGlobalDebugHooks(mJSRuntime)->debuggerHandler)
         xpc_InstallJSDebuggerKeywordHandler(mJSRuntime);
 #endif
+
+    mWatchdogLock = JS_NEW_LOCK();
+    mWatchdogWakeup = JS_NEW_CONDVAR(mWatchdogLock);
+    mWatchdogThread = NULL;
+
 }
 
 // static
@@ -1147,7 +1286,7 @@ XPCJSRuntime::OnJSContextNew(JSContext *cx)
             mStrJSVals[i] = STRING_TO_JSVAL(str);
         }
     }
-    if (!ok)
+    if(!ok)
         return JS_FALSE;
 
     XPCPerThreadData* tls = XPCPerThreadData::GetData(cx);
@@ -1155,7 +1294,7 @@ XPCJSRuntime::OnJSContextNew(JSContext *cx)
         return JS_FALSE;
 
     XPCContext* xpc = new XPCContext(this, cx);
-    if (!xpc)
+    if(!xpc)
         return JS_FALSE;
 
     JS_SetThreadStackLimit(cx, tls->GetStackLimit());
diff --git a/js/src/xpconnect/src/xpcprivate.h b/js/src/xpconnect/src/xpcprivate.h
index b7aa0e90213..be365b0067a 100644
--- a/js/src/xpconnect/src/xpcprivate.h
+++ b/js/src/xpconnect/src/xpcprivate.h
@@ -275,22 +275,22 @@ extern const char XPC_XPCONNECT_CONTRACTID[];
 
 typedef PRMonitor XPCLock;
 
-static inline void xpc_Wait(XPCLock* lock) 
+static inline void xpc_Wait(XPCLock* lock)
     {
         NS_ASSERTION(lock, "xpc_Wait called with null lock!");
 #ifdef DEBUG
-        PRStatus result = 
+        PRStatus result =
 #endif
         PR_Wait(lock, PR_INTERVAL_NO_TIMEOUT);
         NS_ASSERTION(PR_SUCCESS == result, "bad result from PR_Wait!");
     }
 
-static inline void xpc_NotifyAll(XPCLock* lock) 
+static inline void xpc_NotifyAll(XPCLock* lock)
     {
         NS_ASSERTION(lock, "xpc_NotifyAll called with null lock!");
 #ifdef DEBUG
-        PRStatus result = 
-#endif    
+        PRStatus result =
+#endif
         PR_NotifyAll(lock);
         NS_ASSERTION(PR_SUCCESS == result, "bad result from PR_NotifyAll!");
     }
@@ -510,7 +510,7 @@ public:
     NS_IMETHOD Unroot(void *p);
     NS_IMETHOD Traverse(void *p,
                         nsCycleCollectionTraversalCallback &cb);
-    
+
     // nsCycleCollectionLanguageRuntime
     virtual nsresult BeginCycleCollection(nsCycleCollectionTraversalCallback &cb);
     virtual nsresult FinishCycleCollection();
@@ -738,6 +738,10 @@ public:
 
     ~XPCJSRuntime();
 
+    PRIntervalTime GetWatchdogLimit(JSContext *cx);
+    PRBool SetWatchdogLimit(JSContext *cx, PRIntervalTime limit);
+    void WakeupWatchdog(JSContext *cx);
+
 #ifdef XPC_CHECK_WRAPPERS_AT_SHUTDOWN
    void DEBUG_AddWrappedNative(nsIXPConnectWrappedNative* wrapper)
         {XPCAutoLock lock(GetMapLock());
@@ -759,6 +763,9 @@ private:
     XPCJSRuntime(); // no implementation
     XPCJSRuntime(nsXPConnect* aXPConnect);
 
+    PRBool ShutdownWatchdog();
+    static void WatchdogMain(void *args);
+
 private:
     static const char* mStrings[IDX_TOTAL_COUNT];
     jsid mStrIDs[IDX_TOTAL_COUNT];
@@ -786,6 +793,15 @@ private:
     XPCRootSetElem *mObjectHolderRoots;
     JSDHashTable mJSHolders;
     JSDHashTable mClearedGlobalObjects;
+
+    /*
+     * Variables to support watchdog thread.
+     */
+    PRLock *mWatchdogLock;
+    PRCondVar *mWatchdogWakeup;
+    PRBool mWatchdogRunning;
+    PRThread *mWatchdogThread;
+    PRIntervalTime mCurrentInterval;
 };
 
 /***************************************************************************/
@@ -808,26 +824,26 @@ public:
     JSContext* GetJSContext() const {return mJSContext;}
 
     enum LangType {LANG_UNKNOWN, LANG_JS, LANG_NATIVE};
-    
+
     LangType GetCallingLangType() const
         {
             return mCallingLangType;
         }
     LangType SetCallingLangType(LangType lt)
         {
-            LangType tmp = mCallingLangType; 
-            mCallingLangType = lt; 
+            LangType tmp = mCallingLangType;
+            mCallingLangType = lt;
             return tmp;
         }
-    JSBool CallerTypeIsJavaScript() const 
+    JSBool CallerTypeIsJavaScript() const
         {
             return LANG_JS == mCallingLangType;
         }
-    JSBool CallerTypeIsNative() const 
+    JSBool CallerTypeIsNative() const
         {
             return LANG_NATIVE == mCallingLangType;
         }
-    JSBool CallerTypeIsKnown() const 
+    JSBool CallerTypeIsKnown() const
         {
             return LANG_UNKNOWN != mCallingLangType;
         }
@@ -901,6 +917,7 @@ private:
     nsresult mPendingResult;
     nsIXPCSecurityManager* mSecurityManager;
     nsIException* mException;
+    PRIntervalTime mWatchdogLimit;
     LangType mCallingLangType;
     PRUint16 mSecurityManagerFlags;
 
@@ -1244,7 +1261,7 @@ public:
     {return mScriptObjectPrincipal ?
          mScriptObjectPrincipal->GetPrincipal() : nsnull;}
 #endif
-    
+
     JSObject*
     GetPrototypeJSFunction() const {return mPrototypeJSFunction;}
 
@@ -1977,7 +1994,7 @@ public:
 
     // Yes, we *do* need to mark the mScriptableInfo in both cases.
     void Mark() const
-        {mSet->Mark(); 
+        {mSet->Mark();
          if(mScriptableInfo) mScriptableInfo->Mark();}
 
 #ifdef DEBUG
@@ -2499,9 +2516,9 @@ public:
                                             JSObject* aJSObj,
                                             nsISimpleEnumerator** aEnumerate);
 
-    static nsresult GetNamedPropertyAsVariant(XPCCallContext& ccx, 
+    static nsresult GetNamedPropertyAsVariant(XPCCallContext& ccx,
                                               JSObject* aJSObj,
-                                              jsval aName, 
+                                              jsval aName,
                                               nsIVariant** aResult);
 
     virtual ~nsXPCWrappedJSClass();
@@ -2737,7 +2754,7 @@ public:
      * @param scope the default scope to put on the new JSObject's __parent__
      *        chain
      * @param pErr [out] relevant error code, if any.
-     */    
+     */
     static JSBool NativeData2JS(XPCCallContext& ccx, jsval* d, const void* s,
                                 const nsXPTType& type, const nsID* iid,
                                 JSObject* scope, nsresult* pErr);
@@ -2771,7 +2788,7 @@ public:
 
     static JSBool GetNativeInterfaceFromJSObject(XPCCallContext& ccx,
                                                  void** dest, JSObject* src,
-                                                 const nsID* iid, 
+                                                 const nsID* iid,
                                                  nsresult* pErr);
     static JSBool JSObject2NativeInterface(XPCCallContext& ccx,
                                            void** dest, JSObject* src,
@@ -2792,7 +2809,7 @@ public:
      * @param scope the default scope to put on the new JSObjects' __parent__
      *        chain
      * @param pErr [out] relevant error code, if any.
-     */    
+     */
     static JSBool NativeArray2JS(XPCCallContext& ccx,
                                  jsval* d, const void** s,
                                  const nsXPTType& type, const nsID* iid,
@@ -2842,7 +2859,6 @@ public:
 
 private:
     XPCConvert(); // not implemented
-
 };
 
 /***************************************************************************/
@@ -2880,7 +2896,7 @@ public:
     static void ThrowBadResult(nsresult rv, nsresult result, XPCCallContext& ccx);
     static void ThrowBadParam(nsresult rv, uintN paramNum, XPCCallContext& ccx);
 #ifdef XPC_IDISPATCH_SUPPORT
-    static void ThrowCOMError(JSContext* cx, unsigned long COMErrorCode, 
+    static void ThrowCOMError(JSContext* cx, unsigned long COMErrorCode,
                               nsresult rv = NS_ERROR_XPC_COM_ERROR,
                               const EXCEPINFO * exception = nsnull);
 #endif
@@ -3287,7 +3303,7 @@ private:
     static XPCPerThreadData* gThreads;
     static PRUintn           gTLSIndex;
 
-    // Cached value of cx->thread on the main thread. 
+    // Cached value of cx->thread on the main thread.
     static void *sMainJSThread;
 
     // Cached per thread data for the main thread. Only safe to access
@@ -3595,7 +3611,7 @@ private:
     JSContext *mCX;
     jsrefcount mDepth;
 };
-        
+
 
 /*****************************************/
 
@@ -3691,7 +3707,7 @@ public:
     ~AutoResolveName()
         {
 #ifdef DEBUG
-            jsval old = 
+            jsval old =
 #endif
             mTLS->SetResolveName(mOld);
             NS_ASSERTION(old == mCheck, "Bad Nesting!");
@@ -3717,17 +3733,17 @@ public:
     }
     void AutoTrace(JSTracer* trc) {}
 private:
-    XPCMarkableJSVal(); // not implemented    
+    XPCMarkableJSVal(); // not implemented
     jsval  mVal;
     jsval* mValPtr;
-}; 
+};
 
 /***************************************************************************/
-// AutoMarkingPtr is the base class for the various AutoMarking pointer types 
-// below. This system allows us to temporarily protect instances of our garbage 
-// collected types after they are constructed but before they are safely 
+// AutoMarkingPtr is the base class for the various AutoMarking pointer types
+// below. This system allows us to temporarily protect instances of our garbage
+// collected types after they are constructed but before they are safely
 // attached to other rooted objects.
-// This base class has pure virtual support for marking. 
+// This base class has pure virtual support for marking.
 
 class AutoMarkingPtr
 {
@@ -3736,15 +3752,15 @@ public:
         : mNext(nsnull), mTLS(ccx.GetThreadData()) {Link();}
 
     virtual ~AutoMarkingPtr() {Unlink();}
-    
-    void Link() 
+
+    void Link()
         {if(!mTLS) return;
-         AutoMarkingPtr** list = mTLS->GetAutoRootsAdr(); 
+         AutoMarkingPtr** list = mTLS->GetAutoRootsAdr();
          mNext = *list; *list = this;}
 
-    void Unlink() 
+    void Unlink()
         {if(!mTLS) return;
-         AutoMarkingPtr** cur = mTLS->GetAutoRootsAdr(); 
+         AutoMarkingPtr** cur = mTLS->GetAutoRootsAdr();
          while(*cur != this) {
             NS_ASSERTION(*cur, "This object not in list!");
             cur = &(*cur)->mNext;
@@ -3754,7 +3770,7 @@ public:
         }
 
     AutoMarkingPtr* GetNext() {return mNext;}
-    
+
     virtual void TraceJS(JSTracer* trc) = 0;
     virtual void MarkAfterJSFinalize() = 0;
 
@@ -3803,7 +3819,7 @@ DEFINE_AUTO_MARKING_PTR_TYPE(AutoMarkingWrappedNativePtr, XPCWrappedNative)
 DEFINE_AUTO_MARKING_PTR_TYPE(AutoMarkingWrappedNativeTearOffPtr, XPCWrappedNativeTearOff)
 DEFINE_AUTO_MARKING_PTR_TYPE(AutoMarkingWrappedNativeProtoPtr, XPCWrappedNativeProto)
 DEFINE_AUTO_MARKING_PTR_TYPE(AutoMarkingJSVal, XPCMarkableJSVal)
-                                    
+
 #define DEFINE_AUTO_MARKING_ARRAY_PTR_TYPE(class_, type_)                    \
 class class_ : public AutoMarkingPtr                                         \
 {                                                                            \
@@ -3858,9 +3874,9 @@ protected:                                                                   \
 
 DEFINE_AUTO_MARKING_ARRAY_PTR_TYPE(AutoMarkingNativeInterfacePtrArrayPtr,
                                    XPCNativeInterface)
-    
+
 // Note: It looked like I would need one of these AutoMarkingPtr types for
-// XPCNativeScriptableInfo in order to manage marking its 
+// XPCNativeScriptableInfo in order to manage marking its
 // XPCNativeScriptableShared member during construction. But AFAICT we build
 // these and bind them to rooted things so immediately that this just is not
 // needed.
@@ -3903,8 +3919,8 @@ public:
     // the case when mJSVal is JSVAL_STRING, since we don't own the data in
     // that case.
 
-    // We #define and iid so that out module local code can use QI to detect 
-    // if a given nsIVariant is in fact an XPCVariant. 
+    // We #define and iid so that out module local code can use QI to detect
+    // if a given nsIVariant is in fact an XPCVariant.
     NS_DECLARE_STATIC_IID_ACCESSOR(XPCVARIANT_IID)
 
     static XPCVariant* newVariant(XPCCallContext& ccx, jsval aJSVal);
@@ -3922,8 +3938,8 @@ public:
      *        chain
      * @param pErr [out] relevant error code, if any.
      * @param pJSVal [out] the resulting jsval.
-     */    
-    static JSBool VariantDataToJS(XPCCallContext& ccx, 
+     */
+    static JSBool VariantDataToJS(XPCCallContext& ccx,
                                   nsIVariant* variant,
                                   JSObject* scope, nsresult* pErr,
                                   jsval* pJSVal);