Fix linking problem on Windows with ENABLE_LEGACY_NOTIFICATIONS disabled

Source/modules/notifications/NotificationCenter.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2011, 2012 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 14 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * 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 NotificationCenter_h
 #define NotificationCenter_h
 
+#if ENABLE(LEGACY_NOTIFICATIONS)
+
 #include "bindings/v8/ExceptionState.h"
 #include "bindings/v8/ScriptWrappable.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ScriptExecutionContext.h"
 #include "core/html/VoidCallback.h"
 #include "core/platform/Supplementable.h"
 #include "core/platform/Timer.h"
 #include "modules/notifications/Notification.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassRefPtr.h"
@@ skipping 46 matching lines @@
     };
 
     void requestTimedOut(NotificationRequestCallback*);
 
     NotificationClient* m_client;
     HashSet<RefPtr<NotificationRequestCallback> > m_callbacks;
 };
 
 } // namespace WebCore
 
+#endif // ENABLE(LEGACY_NOTIFICATIONS)
+
 #endif // NotificationCenter_h