diff --git a/dom/base/nsIScriptContext.h b/dom/base/nsIScriptContext.h
index 208747027fa..2ad64b3a282 100644
--- a/dom/base/nsIScriptContext.h
+++ b/dom/base/nsIScriptContext.h
@@ -74,8 +74,8 @@ NS_DEFINE_STATIC_IID_ACCESSOR(nsIScriptContextPrincipal,
                               NS_ISCRIPTCONTEXTPRINCIPAL_IID)
 
 #define NS_ISCRIPTCONTEXT_IID \
-{ 0x530d739f, 0x6d79, 0x4919, \
-  { 0x82, 0xb0, 0xef, 0xeb, 0x75, 0xf8, 0xa6, 0x3f } }
+{ 0x2e583bf4, 0x3c1f, 0x432d, \
+  { 0x82, 0x83, 0x8d, 0xee, 0x7e, 0xcc, 0xc8, 0x8b } }
 
 /* This MUST match JSVERSION_DEFAULT.  This version stuff if we don't
    know what language we have is a little silly... */
@@ -226,7 +226,7 @@ public:
    * @param rval out parameter returning result
    **/
   virtual nsresult CallEventHandler(nsISupports* aTarget,
-                                    void *aScope, void* aHandler,
+                                    JSObject* aScope, void* aHandler,
                                     nsIArray *argv, nsIVariant **rval) = 0;
 
   /**
diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp
index ca7400267a4..23e4324935f 100644
--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -1852,8 +1852,8 @@ nsJSContext::CompileFunction(void* aTarget,
 }
 
 nsresult
-nsJSContext::CallEventHandler(nsISupports* aTarget, void *aScope, void *aHandler,
-                              nsIArray *aargv, nsIVariant **arv)
+nsJSContext::CallEventHandler(nsISupports* aTarget, JSObject* aScope,
+                              void *aHandler, nsIArray *aargv, nsIVariant **arv)
 {
   NS_ENSURE_TRUE(mIsInitialized, NS_ERROR_NOT_INITIALIZED);
 
@@ -1875,8 +1875,7 @@ nsJSContext::CallEventHandler(nsISupports* aTarget, void *aScope, void *aHandler
 
   JSAutoRequest ar(mContext);
   JSObject* target = nsnull;
-  nsresult rv = JSObjectFromInterface(aTarget, static_cast<JSObject*>(aScope),
-                                      &target);
+  nsresult rv = JSObjectFromInterface(aTarget, aScope, &target);
   NS_ENSURE_SUCCESS(rv, rv);
 
   js::AutoObjectRooter targetVal(mContext, target);
diff --git a/dom/base/nsJSEnvironment.h b/dom/base/nsJSEnvironment.h
index 64bdcf2a5fe..5aedda2cd59 100644
--- a/dom/base/nsJSEnvironment.h
+++ b/dom/base/nsJSEnvironment.h
@@ -109,7 +109,7 @@ public:
                                        const char *aURL, PRUint32 aLineNo,
                                        PRUint32 aVersion,
                                        nsScriptObjectHolder &aHandler);
-  virtual nsresult CallEventHandler(nsISupports* aTarget, void *aScope,
+  virtual nsresult CallEventHandler(nsISupports* aTarget, JSObject* aScope,
                                     void* aHandler,
                                     nsIArray *argv, nsIVariant **rv);
   virtual nsresult BindCompiledEventHandler(nsISupports *aTarget,