Implement Porter Duff XP with a blend table

include/gpu/GrXferProcessor.h

Index: include/gpu/GrXferProcessor.h
diff --git a/include/gpu/GrXferProcessor.h b/include/gpu/GrXferProcessor.h
index fa9dca211e8fcd24ea0fb81c4c8b743da09a33f8..812d2f67fc55ea0aaf3b5e42d94235ba2123b0db 100644
--- a/include/gpu/GrXferProcessor.h
+++ b/include/gpu/GrXferProcessor.h
@@ -51,10 +51,6 @@ enum GrBlendEquation {
 
 static const int kGrBlendEquationCnt = kLast_GrBlendEquation + 1;
 
-inline bool GrBlendEquationIsAdvanced(GrBlendEquation equation) {
-    return equation >= kFirstAdvancedGrBlendEquation;
-}
-
 /**
  * Coeffecients for alpha-blending.
  */
@@ -143,10 +139,6 @@ public:
          */
         kOverrideColor_OptFlag            = 0x8,
         /**
-         * Set CoverageDrawing_StateBit
-         */
-        kSetCoverageDrawing_OptFlag       = 0x10,
-        /**
          * Can tweak alpha for coverage. Currently this flag should only be used by a batch
          */
         kCanTweakAlphaForCoverage_OptFlag = 0x20,