Add the SharedWorker.workerStart property for high resolution timers.

Source/core/workers/SharedWorker.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 15 matching lines @@
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef SharedWorker_h
 #define SharedWorker_h
 
 #include "core/workers/AbstractWorker.h"
+#include "platform/Supplementable.h"
 
 namespace WebCore {
 
 class ExceptionState;
 
-class SharedWorker : public AbstractWorker, public ScriptWrappable {
+class SharedWorker : public AbstractWorker, public ScriptWrappable, public Supplementable<SharedWorker> {
 public:
     static PassRefPtr<SharedWorker> create(ExecutionContext*, const String& url, const String& name, ExceptionState&);
     virtual ~SharedWorker();
 
     MessagePort* port() const { return m_port.get(); }
 
     virtual const AtomicString& interfaceName() const OVERRIDE;
 
     // Prevents this SharedWorker + JS wrapper from being garbage collected.
     void setPreventGC();
     // Allows this SharedWorker + JS wrapper to be garbage collected.
     void unsetPreventGC();
 
 private:
     explicit SharedWorker(ExecutionContext*);
 
     RefPtr<MessagePort> m_port;
 };
 
 } // namespace WebCore
 
 #endif // SharedWorker_h