[ServiceWorker, PushMessaging] Use ScriptPromiseResolverWithContext.

Source/bindings/v8/ScriptPromiseResolverWithContext.h

Index: Source/bindings/v8/ScriptPromiseResolverWithContext.h
diff --git a/Source/bindings/v8/ScriptPromiseResolverWithContext.h b/Source/bindings/v8/ScriptPromiseResolverWithContext.h
index f373fa9f3e1347a6ea148a86c18c3db1f09632ff..c8b0a6cc4747b3e1de304ac7955e697b20e6f327 100644
--- a/Source/bindings/v8/ScriptPromiseResolverWithContext.h
+++ b/Source/bindings/v8/ScriptPromiseResolverWithContext.h
@@ -62,6 +62,9 @@ public:
             resolveOrRejectImmediately(&m_timer);
     }
 
+    // The returned pointer can be null.

[haraken, 2014/04/14 12:13:17]

(I should have pointed this out in the previous code review but) you don't need
to clear m_scriptState when an ExecutionContext is stopped. NewScriptState
should be valid as long as the holder object is alive.

[yhirano, 2014/04/15 01:02:17]

Done.

+    NewScriptState* scriptState() { return m_scriptState.get(); }
+
     // Note that an empty ScriptPromise will be returned after resolve or
     // reject is called.
     ScriptPromise promise()