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

Source/core/html/HTMLTrackElement.h

Index: Source/core/html/HTMLTrackElement.h
diff --git a/Source/core/html/HTMLTrackElement.h b/Source/core/html/HTMLTrackElement.h
index d4e08fe157ae370562d658ce452fc0e0f7ba2f9f..67541b52af49851afb17abb9c4a075987978ca9c 100644
--- a/Source/core/html/HTMLTrackElement.h
+++ b/Source/core/html/HTMLTrackElement.h
@@ -59,19 +59,19 @@ public:
 
 private:
     explicit HTMLTrackElement(Document&);
-    virtual ~HTMLTrackElement();
+    ~HTMLTrackElement() override;
 
-    virtual void parseAttribute(const QualifiedName&, const AtomicString&) override;
+    void parseAttribute(const QualifiedName&, const AtomicString&) override;
 
-    virtual InsertionNotificationRequest insertedInto(ContainerNode*) override;
+    InsertionNotificationRequest insertedInto(ContainerNode*) override;
 
-    virtual void removedFrom(ContainerNode*) override;
-    virtual bool isURLAttribute(const Attribute&) const override;
+    void removedFrom(ContainerNode*) override;
+    bool isURLAttribute(const Attribute&) const override;
 
     // TextTrackLoaderClient
-    virtual void newCuesAvailable(TextTrackLoader*) override;
-    virtual void cueLoadingCompleted(TextTrackLoader*, bool loadingFailed) override;
-    virtual void newRegionsAvailable(TextTrackLoader*) override;
+    void newCuesAvailable(TextTrackLoader*) override;
+    void cueLoadingCompleted(TextTrackLoader*, bool loadingFailed) override;
+    void newRegionsAvailable(TextTrackLoader*) override;
 
     void setReadyState(ReadyState);