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

Source/core/html/track/VideoTrack.h

Index: Source/core/html/track/VideoTrack.h
diff --git a/Source/core/html/track/VideoTrack.h b/Source/core/html/track/VideoTrack.h
index 0a3578d663e40316771696f3dc3a28e1827372fd..6ad0b37a7b15b9dbf893bb495fb8f80e87d63750 100644
--- a/Source/core/html/track/VideoTrack.h
+++ b/Source/core/html/track/VideoTrack.h
@@ -20,7 +20,7 @@ public:
         return adoptRefWillBeNoop(new VideoTrack(id, kind, label, language, selected));
     }
 
-    virtual ~VideoTrack();
+    ~VideoTrack() override;
     DECLARE_VIRTUAL_TRACE();
 
     bool selected() const { return m_selected; }
@@ -44,8 +44,8 @@ private:
     VideoTrack(const String& id, const AtomicString& kind, const AtomicString& label, const AtomicString& language, bool selected);
 
     // TrackBase
-    virtual bool isValidKind(const AtomicString& kind) const override { return isValidKindKeyword(kind); }
-    virtual AtomicString defaultKind() const override;
+    bool isValidKind(const AtomicString& kind) const override { return isValidKindKeyword(kind); }
+    AtomicString defaultKind() const override;
 
     bool m_selected;
 };