Fix virtual/override/final usage in the rest of Source/core/.

Source/core/frame/Navigator.h

 /*
     Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
 
     This library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 43 matching lines @@
     }
 
     virtual ~Navigator();
 
     bool cookieEnabled() const;
 
     String productSub() const;
     String vendor() const;
     String vendorSub() const;
 
-    virtual String userAgent() const override;
+    String userAgent() const override;
 
     // Relinquishes the storage lock, if one exists.
     void getStorageUpdates();
 
     // NavigatorLanguage
-    virtual Vector<String> languages() override;
+    Vector<String> languages() override;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     explicit Navigator(LocalFrame*);
 };
 
 } // namespace blink
 
 #endif // Navigator_h