Bug 1029933 - Give BackstagePass an Enumerate hook to match its NewResolve hook. r=Waldo

This is required in order to avoid exposing resolve hook effects when
Object.freeze() is invoked on the global. The freeze() call first enumerates
the object, after which point any lazy properties need to be resolve so that
we can safely mark the object as non-extensible.

dom/workers/RuntimeService.cpp

@@ -1077,12 +1077,14 @@ ResolveWorkerClasses(JSContext* aCx, JS::Handle<JSObject*> aObj, JS::Handle<jsid
     }
   }
 
-  bool shouldResolve = false;
-
-  for (uint32_t i = 0; i < ID_COUNT; i++) {
-    if (gStringIDs[i] == aId) {
-      shouldResolve = true;
-      break;
+  // Invoking this function with JSID_VOID means "always resolve".
+  bool shouldResolve = JSID_IS_VOID(aId);
+  if (!shouldResolve) {
+    for (uint32_t i = 0; i < ID_COUNT; i++) {
+      if (gStringIDs[i] == aId) {
+        shouldResolve = true;
+        break;
+      }
     }
   }
 

dom/workers/Workers.h

@@ -170,6 +170,9 @@ enum WorkerPreference
 };
 
 // All of these are implemented in RuntimeService.cpp
+
+// Resolves all of the worker classes onto |aObjp| if one of them matches |aId|
+// or if |aId| is JSID_VOID.
 bool
 ResolveWorkerClasses(JSContext* aCx, JS::Handle<JSObject*> aObj, JS::Handle<jsid> aId,
                      JS::MutableHandle<JSObject*> aObjp);

js/xpconnect/src/XPCRuntimeService.cpp

@@ -30,6 +30,7 @@ NS_IMPL_RELEASE(BackstagePass)
 #define XPC_MAP_CLASSNAME           BackstagePass
 #define XPC_MAP_QUOTED_CLASSNAME   "BackstagePass"
 #define                             XPC_MAP_WANT_NEWRESOLVE
+#define                             XPC_MAP_WANT_ENUMERATE
 #define                             XPC_MAP_WANT_FINALIZE
 #define                             XPC_MAP_WANT_PRECREATE
 
@@ -76,6 +77,22 @@ BackstagePass::NewResolve(nsIXPConnectWrappedNative *wrapper,
     return NS_OK;
 }
 
+NS_IMETHODIMP
+BackstagePass::Enumerate(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
+                         JSObject *objArg, bool *_retval)
+{
+    JS::RootedObject obj(cx, objArg);
+
+    *_retval = JS_EnumerateStandardClasses(cx, obj);
+    NS_ENSURE_TRUE(*_retval, NS_ERROR_FAILURE);
+
+    JS::RootedObject ignored(cx);
+    *_retval = ResolveWorkerClasses(cx, obj, JSID_VOIDHANDLE, &ignored);
+    NS_ENSURE_TRUE(*_retval, NS_ERROR_FAILURE);
+
+    return NS_OK;
+}
+
 /***************************************************************************/
 /* void getInterfaces (out uint32_t count, [array, size_is (count), retval]
                        out nsIIDPtr array); */