Bug 1288033 - part 2 - fixed a compilation error, r=me

dom/workers/WorkerRunnable.cpp

@@ -261,7 +261,7 @@ WorkerRunnable::Run()
     MOZ_ASSERT(IsCanceled(), "Subclass Cancel() didn't set IsCanceled()!");
 
     if (mBehavior == WorkerThreadModifyBusyCount) {
-      mWorkerPrivate->ModifyBusyCountFromWorker(WorkerPrivate::eDecreaseBusyCount);
+      mWorkerPrivate->ModifyBusyCountFromWorker(false);
     }
 
     return NS_OK;