Worker: Call ExternalAsyncTaskFinished() after classic script evaluation

Bug: 778796
Change-Id: I323c022b01bab44be459fca6cd7fcac88ef65e67
Reviewed-on: https://chromium-review.googlesource.com/822313
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524170}

third_party/WebKit/Source/core/workers/WorkerThread.cpp

@@ -448,7 +448,7 @@ void WorkerThread::InitializeOnWorkerThread(
       global_scope_inspector_creation_params->stack_id);
   GlobalScope()->EvaluateClassicScript(script_url, std::move(source_code),
                                        std::move(cached_meta_data));
-  debugger->ExternalAsyncTaskStarted(
+  debugger->ExternalAsyncTaskFinished(
       global_scope_inspector_creation_params->stack_id);
 }