[Worker] Call prepareForShutdown ASAP when terminated forcibly

third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp

Index: third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp
diff --git a/third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp b/third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp
index 1bd3110db62fd7c7ba77ed16b894b06683bf8405..280418cbd40c9fd9003a9c1413dbb7822319d226 100644
--- a/third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp
+++ b/third_party/WebKit/Source/core/loader/ThreadableLoaderTest.cpp
@@ -256,6 +256,9 @@ public:
     void onTearDown() override
     {
         postTaskToWorkerGlobalScope(BLINK_FROM_HERE, createCrossThreadTask(&WorkerThreadableLoaderTestHelper::clearLoader, crossThreadUnretained(this)));
+        WaitableEvent event;
+        postTaskToWorkerGlobalScope(BLINK_FROM_HERE, createCrossThreadTask(&WaitableEvent::signal, crossThreadUnretained(&event)));
+        event.wait();
         m_workerThread->terminateAndWait();
 
         // Needed to clean up the things on the main thread side and