Support colors w/ alpha in SVG 'stop' elements and 'feFlood'

Source/platform/graphics/Color.cpp

 /*
  * Copyright (C) 2003, 2004, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 294 matching lines @@
 
     float v = max(r, max(g, b));
     float multiplier = max(0.0f, (v - 0.33f) / v);
 
     return Color(static_cast<int>(multiplier * r * scaleFactor),
                  static_cast<int>(multiplier * g * scaleFactor),
                  static_cast<int>(multiplier * b * scaleFactor),
                  alpha());
 }
 
+Color Color::modulate(float factor) const
+{
+    return colorWithOverrideAlpha(rgb(), (alpha() / 255.f) * factor);
+}
+
 static int blendComponent(int c, int a)
 {
     // We use white.
     float alpha = a / 255.0f;
     int whiteBlend = 255 - a;
     c -= whiteBlend;
     return static_cast<int>(c / alpha);
 }
 
 const int cStartAlpha = 153; // 60%
@@ skipping 113 matching lines @@
             (color.green() * alpha  + 254) / 255,
             (color.blue() * alpha  + 254) / 255,
             alpha).rgb();
     } else
          pixelColor = color.rgb();
 
     return pixelColor;
 }
 
 } // namespace WebCore