Make all blending up to GrOptDrawState be handled by the xp/xp factory.

src/gpu/SkGpuDevice.cpp

Index: src/gpu/SkGpuDevice.cpp
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index b4b24d9086f74eca31aa23b4c92173db5b40ff33..33b675a0264aad91308b41908fed899c0a6f1083 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -9,6 +9,7 @@
 
 #include "effects/GrBicubicEffect.h"
 #include "effects/GrDashingEffect.h"
+#include "effects/GrPorterDuffXferProcessor.h"
 #include "effects/GrTextureDomain.h"
 #include "effects/GrSimpleTextureEffect.h"
 
@@ -673,7 +674,9 @@ GrTexture* create_mask_GPU(GrContext* context,
         // code path may not be taken. So we use a dst blend coeff of ISA. We
         // could special case AA draws to a dst surface with known alpha=0 to
         // use a zero dst coeff when dual source blending isn't available.
-        tempPaint.setBlendFunc(kOne_GrBlendCoeff, kISC_GrBlendCoeff);
+        GrXPFactory* xpFactory = GrPorterDuffXPFactory::Create(kOne_GrBlendCoeff,
+                                                               kISC_GrBlendCoeff);
+        tempPaint.setXPFactory(xpFactory)->unref();
     }
 
     GrContext::AutoMatrix am;