Update more platform classes to use OVERRIDE / FINAL when needed

Source/platform/graphics/filters/FEMerge.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
  * Copyright (C) 2005 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * 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.
@@ skipping 17 matching lines @@
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
 class PLATFORM_EXPORT FEMerge : public FilterEffect {
 public:
     static PassRefPtr<FEMerge> create(Filter*);
 
     virtual PassRefPtr<SkImageFilter> createImageFilter(SkiaImageFilterBuilder*) OVERRIDE;
 
-    virtual TextStream& externalRepresentation(TextStream&, int indention) const;
+    virtual TextStream& externalRepresentation(TextStream&, int indention) const OVERRIDE;
 
 private:
     FEMerge(Filter*);
 
     virtual void applySoftware() OVERRIDE;
 };
 
 } // namespace WebCore
 
 #endif // FEMerge_h