Bug 1318506 - Label DispatchContentLoaded events with a DocGroup (r=ehsan)

MozReview-Commit-ID: 8vx2Vzvvxhu

dom/base/nsDocument.cpp

@@ -5071,9 +5071,10 @@ nsDocument::UnblockDOMContentLoaded()
 
   MOZ_ASSERT(mReadyState == READYSTATE_INTERACTIVE);
   if (!mSynchronousDOMContentLoaded) {
+    MOZ_RELEASE_ASSERT(NS_IsMainThread());
     nsCOMPtr<nsIRunnable> ev =
       NewRunnableMethod(this, &nsDocument::DispatchContentLoadedEvents);
-    NS_DispatchToCurrentThread(ev);
+    Dispatch("DispatchContentLoadedEvents", TaskCategory::Other, ev.forget());
   } else {
     DispatchContentLoadedEvents();
   }