Add missing virtual keyword for methods with OVERRIDE

Source/platform/graphics/filters/FEColorMatrix.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 42 matching lines @@
 
     static inline void calculateSaturateComponents(float* components, float value);
     static inline void calculateHueRotateComponents(float* components, float value);
 
 private:
     FEColorMatrix(Filter*, ColorMatrixType, const Vector<float>&);
 
     virtual void applySoftware() OVERRIDE;
     virtual bool applySkia() OVERRIDE;
 
-    bool affectsTransparentPixels() OVERRIDE;
+    virtual bool affectsTransparentPixels() OVERRIDE;
 
     ColorMatrixType m_type;
     Vector<float> m_values;
 };
 
 inline void FEColorMatrix::calculateSaturateComponents(float* components, float value)
 {
     components[0] = (0.213 + 0.787 * value);
     components[1] = (0.715 - 0.715 * value);
     components[2] = (0.072 - 0.072 * value);
@@ skipping 17 matching lines @@
     components[5] = 0.072 - cosHue * 0.072 - sinHue * 0.283;
     components[6] = 0.213 - cosHue * 0.213 - sinHue * 0.787;
     components[7] = 0.715 - cosHue * 0.715 + sinHue * 0.715;
     components[8] = 0.072 + cosHue * 0.928 + sinHue * 0.072;
 }
 
 
 } // namespace WebCore
 
 #endif // FEColorMatrix_h