Bug 931887 - No getter_AddRefs for loadInfo.mChannel because HttpChannelChild is not thread-safe, r=bz

dom/workers/WorkerPrivate.cpp

@@ -3759,8 +3759,11 @@ WorkerPrivate::GetLoadInfo(JSContext* aCx, nsPIDOMWindow* aWindow,
       return NS_ERROR_FAILURE;
     }
 
+    // StartAssignment() is used instead getter_AddRefs because, getter_AddRefs
+    // does QI in debug build and, if this worker runs in a child process,
+    // HttpChannelChild will crash because it's not thread-safe.
     rv = ChannelFromScriptURLWorkerThread(aCx, aParent, aScriptURL,
-                                          getter_AddRefs(loadInfo.mChannel));
+                                          loadInfo.mChannel.StartAssignment());
     NS_ENSURE_SUCCESS(rv, rv);
 
     // Now that we've spun the loop there's no guarantee that our parent is