Revert of Fix to set correct output type when blending when we've read dst

src/gpu/effects/GrPorterDuffXferProcessor.cpp

Index: src/gpu/effects/GrPorterDuffXferProcessor.cpp
diff --git a/src/gpu/effects/GrPorterDuffXferProcessor.cpp b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
index f27b16c374af350b4985a138f36435d38b051ede..097854622d67d9538eebe959dfe73080eb20abf3 100644
--- a/src/gpu/effects/GrPorterDuffXferProcessor.cpp
+++ b/src/gpu/effects/GrPorterDuffXferProcessor.cpp
@@ -68,10 +68,6 @@
         
         fsBuilder->codeAppendf("%s = %s * %s;", args.fOutputPrimary, args.fInputColor,
                                args.fInputCoverage);
-        if (GrPorterDuffXferProcessor::kCombineWithDst_PrimaryOutputType == xp.primaryOutputType()){
-            fsBuilder->codeAppendf("%s += (vec4(1.0) - %s) * %s;", args.fOutputPrimary,
-                                   args.fInputCoverage, fsBuilder->dstColor());
-        }
     }
 
     virtual void setData(const GrGLProgramDataManager&, const GrXferProcessor&) SK_OVERRIDE {};
@@ -79,7 +75,6 @@
     static void GenKey(const GrProcessor& processor, const GrGLCaps& caps,
                        GrProcessorKeyBuilder* b) {
         const GrPorterDuffXferProcessor& xp = processor.cast<GrPorterDuffXferProcessor>();
-        b->add32(xp.primaryOutputType());
         b->add32(xp.secondaryOutputType());
     };
 
@@ -94,7 +89,6 @@
     : fSrcBlend(srcBlend)
     , fDstBlend(dstBlend)
     , fBlendConstant(constant)
-    , fPrimaryOutputType(kModulate_PrimaryOutputType) 
     , fSecondaryOutputType(kNone_SecondaryOutputType) {
     this->initClassID<GrPorterDuffXferProcessor>();
 }
@@ -158,10 +152,6 @@
                 fSecondaryOutputType = kCoverageISC_SecondaryOutputType;
                 fDstBlend = (GrBlendCoeff)GrGpu::kIS2C_GrBlendCoeff;
             }
-        } else if (readsDst &&
-                   kOne_GrBlendCoeff == fSrcBlend &&
-                   kZero_GrBlendCoeff == fDstBlend) {
-            fPrimaryOutputType = kCombineWithDst_PrimaryOutputType;
         }
     }
 }