Move isValid/isCurrentColor from Color to StyleColor

Source/core/platform/graphics/DrawLooper.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * 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 35 matching lines @@
 void DrawLooper::addUnmodifiedContent()
 {
     SkLayerDrawLooper::LayerInfo info;
     m_skDrawLooper->addLayerOnTop(info);
 }
 
 void DrawLooper::addShadow(const FloatSize& offset, float blur, const Color& color,
     ShadowTransformMode shadowTransformMode, ShadowAlphaMode shadowAlphaMode)
 {
     // Detect when there's no effective shadow.
-    if (!color.isValid() || !color.alpha())
+    if (!color.alpha())
         return;
 
-    SkColor skColor;
-    if (color.isValid())
-        skColor = color.rgb();
-    else
-        skColor = SkColorSetARGB(0xFF / 3, 0, 0, 0); // "std" apple shadow color.
+    SkColor skColor = color.rgb();
 
     SkLayerDrawLooper::LayerInfo info;
 
     switch (shadowAlphaMode) {
     case ShadowRespectsAlpha:
         info.fColorMode = SkXfermode::kDst_Mode;
         break;
     case ShadowIgnoresAlpha:
         info.fColorMode = SkXfermode::kSrc_Mode;
         break;
@@ skipping 16 matching lines @@
         SkMaskFilter* mf = SkBlurMaskFilter::Create((double)blur / 2.0,
             SkBlurMaskFilter::kNormal_BlurStyle, mfFlags);
         SkSafeUnref(paint->setMaskFilter(mf));
     }
 
     SkColorFilter* cf = SkColorFilter::CreateModeFilter(skColor, SkXfermode::kSrcIn_Mode);
     SkSafeUnref(paint->setColorFilter(cf));
 }
 
 } // namespace WebCore