Add the navigator.serviceWorker.waiting property.

Source/modules/serviceworkers/ServiceWorker.h

Index: Source/modules/serviceworkers/ServiceWorker.h
diff --git a/Source/modules/serviceworkers/ServiceWorker.h b/Source/modules/serviceworkers/ServiceWorker.h
index 111e02de8ee4a3df5522e9c7255880d608c7bbaa..58a40ea43e8145cdfe3a95e98223ac0bee06f158 100644
--- a/Source/modules/serviceworkers/ServiceWorker.h
+++ b/Source/modules/serviceworkers/ServiceWorker.h
@@ -52,15 +52,13 @@ class ServiceWorker
     , public ScriptWrappable
     , public blink::WebServiceWorkerProxy {
 public:
-    static PassRefPtr<ServiceWorker> create(ExecutionContext*, PassOwnPtr<blink::WebServiceWorker>);
-
     virtual ~ServiceWorker() { }
 
     // For CallbackPromiseAdapter
     typedef blink::WebServiceWorker WebType;
     static PassRefPtr<ServiceWorker> from(ScriptPromiseResolverWithContext*, WebType* worker);
 
-    static PassRefPtr<ServiceWorker> from(ScriptState*, WebType*);
+    static PassRefPtr<ServiceWorker> from(ExecutionContext*, WebType*);
 
     void postMessage(PassRefPtr<SerializedScriptValue> message, const MessagePortArray*, ExceptionState&);
 
@@ -79,6 +77,7 @@ public:
 private:
     class ThenFunction;
 
+    static PassRefPtr<ServiceWorker> create(ExecutionContext*, PassOwnPtr<blink::WebServiceWorker>);
     ServiceWorker(ExecutionContext*, PassOwnPtr<blink::WebServiceWorker>);
     void onPromiseResolved();
     void waitOnPromise(ScriptPromise);