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

Source/core/html/LabelableElement.h

 /*
  * Copyright (C) 2012 Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 24 matching lines @@
 #include "core/html/HTMLElement.h"
 
 namespace blink {
 
 class LabelsNodeList;
 
 // LabelableElement represents "labelable element" defined in the HTML
 // specification, and provides the implementation of the "labels" attribute.
 class CORE_EXPORT LabelableElement : public HTMLElement {
 public:
-    virtual ~LabelableElement();
+    ~LabelableElement() override;
     PassRefPtrWillBeRawPtr<LabelsNodeList> labels();
     virtual bool supportLabels() const { return false; }
 
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     LabelableElement(const QualifiedName& tagName, Document&);
 
 private:
-    virtual bool isLabelable() const override final { return true; }
+    bool isLabelable() const final { return true; }
 };
 
 inline bool isLabelableElement(const HTMLElement& element)
 {
     return element.isLabelable();
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(LabelableElement);
 
 } // namespace blink
 
 #endif