Bug 1288031 - CloseHandlerStarted() is called wrongly in WorkerPrivate, r=khuey

dom/workers/WorkerPrivate.cpp

@@ -605,7 +605,9 @@ class CloseEventRunnable final : public WorkerRunnable
 public:
   explicit CloseEventRunnable(WorkerPrivate* aWorkerPrivate)
   : WorkerRunnable(aWorkerPrivate, WorkerThreadUnchangedBusyCount)
-  { }
+  {
+    aWorkerPrivate->CloseHandlerStarted();
+  }
 
 private:
   virtual bool
@@ -623,8 +625,6 @@ private:
   virtual bool
   WorkerRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate) override
   {
-    aWorkerPrivate->CloseHandlerStarted();
-
     WorkerGlobalScope* globalScope = aWorkerPrivate->GlobalScope();
 
     RefPtr<Event> event = NS_NewDOMEvent(globalScope, nullptr, nullptr);