Implement support for KHR_blend_equation_advanced

src/gpu/SkGr.cpp

Index: src/gpu/SkGr.cpp
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index b44276cd4eedbcb46278d4eca6c46c2deba86a1c..b439a546cebdf7fb9591113931ad85ba52ffcebe 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -650,7 +650,7 @@ void SkPaint2GrPaintNoShader(GrContext* context, GrRenderTarget* rt, const SkPai
 
     SkXfermode* mode = skPaint.getXfermode();
     GrXPFactory* xpFactory = NULL;
-    if (!SkXfermode::AsXPFactory(mode, &xpFactory)) {
+    if (!SkXfermode::AsXPFactory(mode, context, &xpFactory)) {
         // Fall back to src-over
         xpFactory = GrPorterDuffXPFactory::Create(SkXfermode::kSrcOver_Mode);
     }