Add blink-side binding code for navigator.serviceWorker.current

Source/modules/serviceworkers/ServiceWorkerContainer.h

Index: Source/modules/serviceworkers/ServiceWorkerContainer.h
diff --git a/Source/modules/serviceworkers/ServiceWorkerContainer.h b/Source/modules/serviceworkers/ServiceWorkerContainer.h
index 31cddf641efdd610e7755af113afa5c09a6e2083..19612b22f6e71420a36504c0e4c0aca73ec3a04f 100644
--- a/Source/modules/serviceworkers/ServiceWorkerContainer.h
+++ b/Source/modules/serviceworkers/ServiceWorkerContainer.h
@@ -35,6 +35,7 @@
 #include "bindings/v8/ScriptWrappable.h"
 #include "core/dom/ContextLifecycleObserver.h"
 #include "core/frame/DOMWindowLifecycleObserver.h"
+#include "modules/serviceworkers/ServiceWorker.h"
 #include "public/platform/WebServiceWorkerProviderClient.h"
 #include "wtf/Forward.h"
 #include "wtf/PassRefPtr.h"
@@ -66,6 +67,8 @@ public:
     ScriptPromise registerServiceWorker(ExecutionContext*, const String& pattern, const Dictionary&);
     ScriptPromise unregisterServiceWorker(ExecutionContext*, const String& scope = String());
 
+    PassRefPtr<ServiceWorker> current() { return m_current; }
+
     // WebServiceWorkerProviderClient overrides.
     virtual void setCurrentServiceWorker(blink::WebServiceWorker*) OVERRIDE;
     virtual void dispatchMessageEvent(const blink::WebString& message, const blink::WebMessagePortChannelArray&) OVERRIDE;