ScriptPromise should check the constructor paraemter.

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 57 matching lines @@
 }
 
 void WaitUntilObserver::didDispatchEvent()
 {
     decrementPendingActivity();
 }
 
 void WaitUntilObserver::waitUntil(const ScriptValue& value)
 {
     incrementPendingActivity();
-    ScriptPromise(value).then(
+    ScriptPromise::cast(value).then(
         ThenFunction::create(this, ThenFunction::Fulfilled),
         ThenFunction::create(this, ThenFunction::Rejected));
 }
 
 WaitUntilObserver::WaitUntilObserver(ExecutionContext* context, int eventID)
     : ContextLifecycleObserver(context)
     , m_eventID(eventID)
     , m_pendingActivity(0)
 {
 }
@@ skipping 13 matching lines @@
 {
     ASSERT(m_pendingActivity > 0);
     if (--m_pendingActivity || !executionContext())
         return;
 
     ServiceWorkerGlobalScopeClient::from(executionContext())->didHandleInstallEvent(m_eventID);
     observeContext(0);
 }
 
 } // namespace WebCore