Add ServiceWorker InstallPhaseEvent.waitUntil() layout test.

Source/modules/serviceworkers/WaitUntilObserver.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "modules/serviceworkers/WaitUntilObserver.h"
 
 #include "bindings/v8/ScriptFunction.h"
 #include "bindings/v8/ScriptPromise.h"
 #include "bindings/v8/ScriptValue.h"
@@ skipping 90 matching lines @@
 }
 
 void WaitUntilObserver::incrementPendingActivity()
 {
     ++m_pendingActivity;
 }
 
 void WaitUntilObserver::decrementPendingActivity()
 {
     ASSERT(m_pendingActivity > 0);
-    if (--m_pendingActivity || !executionContext())
+    if (!executionContext() || (!m_hasError && --m_pendingActivity))

[jsbell, 2014/07/01 16:16:48]

Is the assertion in the destructor still valid if some decrement requests are
ignored?

[xiang, 2014/07/02 05:10:43]

I will remove assertion in desctructor as it's not valid anymore.

         return;
 
     ServiceWorkerGlobalScopeClient* client = ServiceWorkerGlobalScopeClient::from(executionContext());
     blink::WebServiceWorkerEventResult result = m_hasError ? blink::WebServiceWorkerEventResultRejected : blink::WebServiceWorkerEventResultCompleted;
     switch (m_type) {
     case Activate:
         client->didHandleActivateEvent(m_eventID, result);
         break;
     case Install:
         client->didHandleInstallEvent(m_eventID, result);
         break;
     }
     observeContext(0);
 }
 
 } // namespace WebCore