Bug 947778, return early from SetEventHandler when ELM can't find the global jsobject, r=bz

content/events/src/nsEventListenerManager.cpp

@@ -720,6 +720,8 @@ nsEventListenerManager::SetEventHandler(nsIAtom *aName,
   nsIScriptContext* context = global->GetScriptContext();
   NS_ENSURE_TRUE(context, NS_ERROR_FAILURE);
 
+  NS_ENSURE_STATE(global->GetGlobalJSObject());
+
   JSAutoRequest ar(context->GetNativeContext());
   JS::Rooted<JSObject*> scope(context->GetNativeContext(),
                               global->GetGlobalJSObject());