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

Source/core/html/track/TrackEvent.h

Index: Source/core/html/track/TrackEvent.h
diff --git a/Source/core/html/track/TrackEvent.h b/Source/core/html/track/TrackEvent.h
index cc62e5a1f9c82e6fbb158d4fc7a814840a21ffef..dc26fc3408dcb497bfcdacfbdf5e91963f3e5a32 100644
--- a/Source/core/html/track/TrackEvent.h
+++ b/Source/core/html/track/TrackEvent.h
@@ -37,7 +37,7 @@ class VideoTrackOrAudioTrackOrTextTrack;
 class TrackEvent final : public Event {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    virtual ~TrackEvent();
+    ~TrackEvent() override;
 
     static PassRefPtrWillBeRawPtr<TrackEvent> create()
     {
@@ -55,7 +55,7 @@ public:
         return adoptRefWillBeNoop(new TrackEvent(type, track));
     }
 
-    virtual const AtomicString& interfaceName() const override;
+    const AtomicString& interfaceName() const override;
 
     void track(VideoTrackOrAudioTrackOrTextTrack&);