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

Source/core/css/CSSKeyframesRule.h

Index: Source/core/css/CSSKeyframesRule.h
diff --git a/Source/core/css/CSSKeyframesRule.h b/Source/core/css/CSSKeyframesRule.h
index f8d505690f3e4f769cae55a64a8c590c7c91df63..69574322c5f791ed31107b5332096247941f1a0c 100644
--- a/Source/core/css/CSSKeyframesRule.h
+++ b/Source/core/css/CSSKeyframesRule.h
@@ -84,10 +84,10 @@ public:
         return adoptRefWillBeNoop(new CSSKeyframesRule(rule, sheet));
     }
 
-    virtual ~CSSKeyframesRule();
+    ~CSSKeyframesRule() override;
 
-    virtual String cssText() const override;
-    virtual void reattach(StyleRuleBase*) override;
+    String cssText() const override;
+    void reattach(StyleRuleBase*) override;
 
     String name() const { return m_keyframesRule->name(); }
     void setName(const String&);
@@ -113,7 +113,7 @@ public:
 private:
     CSSKeyframesRule(StyleRuleKeyframes*, CSSStyleSheet* parent);
 
-    virtual CSSRule::Type type() const override { return KEYFRAMES_RULE; }
+    CSSRule::Type type() const override { return KEYFRAMES_RULE; }
 
     RefPtrWillBeMember<StyleRuleKeyframes> m_keyframesRule;
     mutable WillBeHeapVector<RefPtrWillBeMember<CSSKeyframeRule>> m_childRuleCSSOMWrappers;