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

Source/core/css/CSSCrossfadeValue.h

Index: Source/core/css/CSSCrossfadeValue.h
diff --git a/Source/core/css/CSSCrossfadeValue.h b/Source/core/css/CSSCrossfadeValue.h
index cb71539951a6e806d26624905c460f7c3196400b..9e23bfa11f4c62fb7704a65628657a152cacb3ec 100644
--- a/Source/core/css/CSSCrossfadeValue.h
+++ b/Source/core/css/CSSCrossfadeValue.h
@@ -88,8 +88,8 @@ private:
         : m_ownerValue(ownerValue)
         , m_ready(false) { }
 
-        virtual ~CrossfadeSubimageObserverProxy() { }
-        virtual void imageChanged(ImageResource*, const IntRect* = nullptr) override;
+        ~CrossfadeSubimageObserverProxy() override { }
+        void imageChanged(ImageResource*, const IntRect* = nullptr) override;
         void setReady(bool ready) { m_ready = ready; }
     private:
         CSSCrossfadeValue* m_ownerValue;