diff --git a/mozilla/content/xbl/src/nsXBLPrototypeBinding.cpp b/mozilla/content/xbl/src/nsXBLPrototypeBinding.cpp
index 3ea85265a8c..9adf836decf 100644
--- a/mozilla/content/xbl/src/nsXBLPrototypeBinding.cpp
+++ b/mozilla/content/xbl/src/nsXBLPrototypeBinding.cpp
@@ -361,12 +361,6 @@ nsXBLPrototypeBinding::Traverse(nsCycleCollectionTraversalCallback &cb) const
     mInsertionPointTable->Enumerate(TraverseInsertionPoint, &cb);
   if (mInterfaceTable)
     mInterfaceTable->Enumerate(TraverseBinding, &cb);
-
-  nsXBLPrototypeHandler* curr = mPrototypeHandler;
-  while (curr) {
-    curr->Traverse(cb);
-    curr = curr->GetNextHandler();
-  }
 }
 
 void
diff --git a/mozilla/content/xbl/src/nsXBLPrototypeHandler.cpp b/mozilla/content/xbl/src/nsXBLPrototypeHandler.cpp
index ed4b8f4d59b..fbaf584d272 100644
--- a/mozilla/content/xbl/src/nsXBLPrototypeHandler.cpp
+++ b/mozilla/content/xbl/src/nsXBLPrototypeHandler.cpp
@@ -161,12 +161,6 @@ nsXBLPrototypeHandler::~nsXBLPrototypeHandler()
   delete mNextHandler;
 }
 
-void
-nsXBLPrototypeHandler::Traverse(nsCycleCollectionTraversalCallback &cb) const
-{
-  cb.NoteXPCOMChild(mGlobalForCachedHandler);
-}
-
 void
 nsXBLPrototypeHandler::Trace(TraceCallback aCallback, void *aClosure) const
 {
@@ -375,12 +369,16 @@ nsXBLPrototypeHandler::EnsureEventHandler(nsIScriptGlobalObject* aGlobal,
                                           nsScriptObjectHolder &aHandler)
 {
   // Check to see if we've already compiled this
-  if (mCachedHandler && mGlobalForCachedHandler == aGlobal) {
-    aHandler.set(mCachedHandler);
-    if (!aHandler)
-      return NS_ERROR_FAILURE;
-
-    return NS_OK;
+  if (mCachedHandler) {
+    nsCOMPtr<nsIScriptGlobalObject> cachedGlobal =
+      do_QueryReferent(mGlobalForCachedHandler);
+    if (cachedGlobal == aGlobal) {
+      aHandler.set(mCachedHandler);
+      if (!aHandler)
+        return NS_ERROR_FAILURE;
+  
+      return NS_OK;
+    }
   }
 
   // Ensure that we have something to compile
@@ -401,7 +399,7 @@ nsXBLPrototypeHandler::EnsureEventHandler(nsIScriptGlobalObject* aGlobal,
   NS_ENSURE_SUCCESS(rv, rv);
 
   mCachedHandler = aHandler;
-  mGlobalForCachedHandler = aGlobal;
+  mGlobalForCachedHandler = do_GetWeakReference(aGlobal);
 
   return NS_OK;
 }
diff --git a/mozilla/content/xbl/src/nsXBLPrototypeHandler.h b/mozilla/content/xbl/src/nsXBLPrototypeHandler.h
index ff664edb00b..3afa872abcc 100644
--- a/mozilla/content/xbl/src/nsXBLPrototypeHandler.h
+++ b/mozilla/content/xbl/src/nsXBLPrototypeHandler.h
@@ -153,7 +153,6 @@ public:
     return (mType & NS_HANDLER_ALLOW_UNTRUSTED) != 0;
   }
 
-  void Traverse(nsCycleCollectionTraversalCallback &cb) const;
   void Trace(TraceCallback aCallback, void *aClosure) const;
   void Unlink();
 	
@@ -233,7 +232,7 @@ protected:
 
   // cache a handler to avoid compiling each time
   void *mCachedHandler;
-  nsCOMPtr<nsIScriptGlobalObject> mGlobalForCachedHandler;
+  nsWeakPtr mGlobalForCachedHandler;
 
   // Prototype handlers are chained. We own the next handler in the chain.
   nsXBLPrototypeHandler* mNextHandler;