Bug 1183824 - Remove NS_ENSURE_TRUE(mCallback, NS_ERROR_NOT_INITIALIZED) warning from nsFrameMessageManager::DispatchAsyncMessageInternal. r=smaug

dom/base/nsFrameMessageManager.cpp

@@ -800,7 +800,10 @@ nsFrameMessageManager::DispatchAsyncMessageInternal(JSContext* aCx,
     return NS_OK;
   }
 
-  NS_ENSURE_TRUE(mCallback, NS_ERROR_NOT_INITIALIZED);
+  if (!mCallback) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
   if (!mCallback->DoSendAsyncMessage(aCx, aMessage, aData, aCpows, aPrincipal)) {
     return NS_ERROR_FAILURE;
   }