Fix virtual/override/final usage in Source/core/{animation,css,style}/.

Source/core/css/CSSGroupingRule.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * (C) 2002-2003 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2002, 2006, 2008, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig (sam@webkit.org)
  *
  * 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 17 matching lines @@
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class ExceptionState;
 class CSSRuleList;
 
 class CSSGroupingRule : public CSSRule {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    virtual ~CSSGroupingRule();
+    ~CSSGroupingRule() override;
 
-    virtual void reattach(StyleRuleBase*) override;
+    void reattach(StyleRuleBase*) override;
 
     CSSRuleList* cssRules() const override;
 
     unsigned insertRule(const String& rule, unsigned index, ExceptionState&);
     void deleteRule(unsigned index, ExceptionState&);
 
     // For CSSRuleList
     unsigned length() const;
     CSSRule* item(unsigned index) const;
 
     DECLARE_VIRTUAL_TRACE();
 
 protected:
     CSSGroupingRule(StyleRuleGroup* groupRule, CSSStyleSheet* parent);
 
     void appendCSSTextForItems(StringBuilder&) const;
 
     RefPtrWillBeMember<StyleRuleGroup> m_groupRule;
     mutable WillBeHeapVector<RefPtrWillBeMember<CSSRule>> m_childRuleCSSOMWrappers;
     mutable OwnPtrWillBeMember<CSSRuleList> m_ruleListCSSOMWrapper;
 };
 
 } // namespace blink
 
 #endif // CSSGroupingRule_h