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

Source/core/events/MutationEvent.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, 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 MutationEvent_h
 
 #include "core/events/Event.h"
 #include "core/dom/Node.h"
 
 namespace blink {
 
 class MutationEvent final : public Event {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    virtual ~MutationEvent();
+    ~MutationEvent() override;
 
     enum AttrChangeType {
         MODIFICATION    = 1, // NOLINT
         ADDITION        = 2, // NOLINT
         REMOVAL         = 3  // NOLINT
     };
 
     static PassRefPtrWillBeRawPtr<MutationEvent> create()
     {
         return adoptRefWillBeNoop(new MutationEvent);
     }
 
     static PassRefPtrWillBeRawPtr<MutationEvent> create(
         const AtomicString& type, bool canBubble, PassRefPtrWillBeRawPtr<Node> relatedNode = nullptr,
         const String& prevValue = String(), const String& newValue = String(), const String& attrName = String(), unsigned short attrChange = 0)
     {
         return adoptRefWillBeNoop(new MutationEvent(type, canBubble, false, relatedNode, prevValue, newValue, attrName, attrChange));
     }
 
     void initMutationEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<Node> relatedNode, const String& prevValue, const String& newValue, const String& attrName, unsigned short attrChange);
 
     Node* relatedNode() const { return m_relatedNode.get(); }
     String prevValue() const { return m_prevValue; }
     String newValue() const { return m_newValue; }
     String attrName() const { return m_attrName; }
     unsigned short attrChange() const { return m_attrChange; }
 
-    virtual const AtomicString& interfaceName() const override;
+    const AtomicString& interfaceName() const override;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     MutationEvent();
     MutationEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<Node> relatedNode, const String& prevValue, const String& newValue, const String& attrName, unsigned short attrChange);
 
     RefPtrWillBeMember<Node> m_relatedNode;
     String m_prevValue;
     String m_newValue;
     String m_attrName;
     unsigned short m_attrChange;
 };
 
 } // namespace blink
 
 #endif // MutationEvent_h