fix the visual diff of raster vs gpu -- vertices_80

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "effects/GrBicubicEffect.h"
@@ skipping 1631 matching lines @@
 #if 0
             return
 #endif
         }
     }
 
     SkAutoSTMalloc<128, GrColor> convertedColors(0);
     if (NULL != colors) {
         // need to convert byte order and from non-PM to PM
         convertedColors.reset(vertexCount);
+        SkColor color;
         for (int i = 0; i < vertexCount; ++i) {
-            convertedColors[i] = SkColor2GrColor(colors[i]);
+            color = colors[i];
+            if (paint.getAlpha() != 255) {
+                color = SkColorSetA(color, SkMulDiv255Round(SkColorGetA(color), paint.getAlpha()));
+            }
+            convertedColors[i] = SkColor2GrColor(color);
         }
         colors = convertedColors.get();
     }
     fContext->drawVertices(grPaint,
                            gVertexMode2PrimitiveType[vmode],
                            vertexCount,
                            vertices,
                            texs,
                            colors,
                            indices,
@@ skipping 322 matching lines @@
         GrCachedLayer* layer = fContext->getLayerCache()->findLayerOrCreate(picture, i);
 
         if (NULL != layer->getTexture()) {
             fContext->unlockScratchTexture(layer->getTexture());
             layer->setTexture(NULL);
         }
     }
 
     return true;
 }