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

Source/core/svg/SVGUnknownElement.h

 /*
  * Copyright (C) 2013 Samsung Electronics. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 30 matching lines @@
 //
 // The main purpose of this class at the moment is to override layoutObjectIsNeeded() to return
 // false to make sure we don't attempt to layout such elements.
 class SVGUnknownElement final : public SVGElement {
 public:
     DECLARE_ELEMENT_FACTORY_WITH_TAGNAME(SVGUnknownElement);
 
 private:
     SVGUnknownElement(const QualifiedName&, Document&);
 
-    virtual bool layoutObjectIsNeeded(const ComputedStyle&) override { return false; }
+    bool layoutObjectIsNeeded(const ComputedStyle&) override { return false; }
 };
 
 } // namespace blink
 
 #endif // SVGUnknownElement_h