Fix virtual/override/final usage in Source/core/html/.

Source/core/html/HTMLRubyElement.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef HTMLRubyElement_h
 #define HTMLRubyElement_h
 
 #include "core/html/HTMLElement.h"
 
 namespace blink {
 
 // <ruby> is an HTMLElement in script, but we use a separate interface here
 // so HTMLElement's createLayoutObject doesn't need to know about it.
 class HTMLRubyElement final : public HTMLElement {
 public:
     DECLARE_NODE_FACTORY(HTMLRubyElement);
 
 private:
     explicit HTMLRubyElement(Document&);
 
-    virtual LayoutObject* createLayoutObject(const ComputedStyle&) override;
+    LayoutObject* createLayoutObject(const ComputedStyle&) override;
 };
 
 } // namespace
 
 #endif