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 3161c81604ade16970253dfb1c419829aaa0bd6a..94060cd54815c11cb2adb32f9fc9db816f641592 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -650,7 +650,7 @@ bool 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
         // return false here?
         xpFactory = GrPorterDuffXPFactory::Create(SkXfermode::kSrcOver_Mode);