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

Source/core/html/track/LoadableTextTrack.h

Index: Source/core/html/track/LoadableTextTrack.h
diff --git a/Source/core/html/track/LoadableTextTrack.h b/Source/core/html/track/LoadableTextTrack.h
index e1468e9817f1b2b8a57fe31a7cc5a15ce3eafd03..d68174e13f1a2f2a56453038d0d86ecd138274a2 100644
--- a/Source/core/html/track/LoadableTextTrack.h
+++ b/Source/core/html/track/LoadableTextTrack.h
@@ -40,10 +40,10 @@ public:
     {
         return adoptRefWillBeNoop(new LoadableTextTrack(track));
     }
-    virtual ~LoadableTextTrack();
+    ~LoadableTextTrack() override;
 
     // TextTrack method.
-    virtual void setMode(const AtomicString&) override;
+    void setMode(const AtomicString&) override;
 
     void addRegions(const WillBeHeapVector<RefPtrWillBeMember<VTTRegion>>&);
     using TextTrack::addListOfCues;
@@ -54,7 +54,7 @@ public:
     void clearTrackElement();
 #endif
 
-    virtual bool isDefault() const override;
+    bool isDefault() const override;
 
     DECLARE_VIRTUAL_TRACE();