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

Source/core/svg/SVGStopElement.cpp

 /*
  * Copyright (C) 2004, 2005, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007 Rob Buis <buis@kde.org>
  *
  * 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,
@@ skipping 97 matching lines @@
 Color SVGStopElement::stopColorIncludingOpacity() const
 {
     RenderStyle* style = renderer() ? renderer()->style() : 0;
     // FIXME: This check for null style exists to address Bug WK 90814, a rare crash condition in
     // which the renderer or style is null. This entire class is scheduled for removal (Bug WK 86941)
     // and we will tolerate this null check until then.
     if (!style || !style->svgStyle())
         return Color(Color::transparent, true); // Transparent black.
 
     const SVGRenderStyle* svgStyle = style->svgStyle();
-    return colorWithOverrideAlpha(svgStyle->stopColor().rgb(), svgStyle->stopOpacity());
+    return svgStyle->stopColor().modulate(svgStyle->stopOpacity());
 }
 
 }