Fix virtual/override/final usage in the rest of Source/core/.

Source/core/events/ClipboardEvent.h

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 14 matching lines @@
 #define ClipboardEvent_h
 
 #include "core/clipboard/DataTransfer.h"
 #include "core/events/Event.h"
 
 namespace blink {
 
 class ClipboardEvent final : public Event {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    virtual ~ClipboardEvent();
+    ~ClipboardEvent() override;
     static PassRefPtrWillBeRawPtr<ClipboardEvent> create()
     {
         return adoptRefWillBeNoop(new ClipboardEvent());
     }
 
     static PassRefPtrWillBeRawPtr<ClipboardEvent> create(const AtomicString& type, bool canBubble, bool cancelable, DataTransfer* dataTransfer)
     {
         return adoptRefWillBeNoop(new ClipboardEvent(type, canBubble, cancelable, dataTransfer));
     }
 
     DataTransfer* clipboardData() const { return m_clipboardData.get(); }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     ClipboardEvent();
     ClipboardEvent(const AtomicString& type, bool canBubble, bool cancelable, DataTransfer* clipboardData);
 
-    virtual const AtomicString& interfaceName() const override;
-    virtual bool isClipboardEvent() const override;
+    const AtomicString& interfaceName() const override;
+    bool isClipboardEvent() const override;
 
     PersistentWillBeMember<DataTransfer> m_clipboardData;
 };
 
 } // namespace blink
 
 #endif // ClipboardEvent_h