Remove gpu shader optimatization for solid white or trans black colors

src/gpu/GrDrawState.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDrawState.h"
 #include "GrPaint.h"
 
@@ skipping 391 matching lines @@
     if (kOne_GrBlendCoeff == *srcCoeff &&
         kZero_GrBlendCoeff == *dstCoeff &&
         this->willEffectReadDstColor()) {
         // In this case the shader will fully resolve the color, coverage, and dst and we don't
         // need blending.
         return kDisableBlend_BlendOptFlag;
     }
     return kNone_BlendOpt;
 }
 
+bool GrDrawState::canIgnoreColorAttribute() const {
+    if (fBlendOptFlags & kInvalid_BlendOptFlag) {
+        this->getBlendOpts();
+    }
+    return SkToBool(fBlendOptFlags & (GrDrawState::kEmitTransBlack_BlendOptFlag |
+                                      GrDrawState::kEmitCoverage_BlendOptFlag));
+}
+
+
 ////////////////////////////////////////////////////////////////////////////////
 
 void GrDrawState::AutoViewMatrixRestore::restore() {
     if (NULL != fDrawState) {
         SkDEBUGCODE(--fDrawState->fBlockEffectRemovalCnt;)
         fDrawState->fViewMatrix = fViewMatrix;
         SkASSERT(fDrawState->numColorStages() >= fNumColorStages);
         int numCoverageStages = fSavedCoordChanges.count() - fNumColorStages;
         SkASSERT(fDrawState->numCoverageStages() >= numCoverageStages);
 
@@ skipping 66 matching lines @@
         fDrawState->fColorStages[s].saveCoordChange(&fSavedCoordChanges[i]);
         fDrawState->fColorStages[s].localCoordChange(coordChangeMatrix);
     }
 
     int numCoverageStages = fDrawState->numCoverageStages();
     for (int s = 0; s < numCoverageStages; ++s, ++i) {
         fDrawState->fCoverageStages[s].saveCoordChange(&fSavedCoordChanges[i]);
         fDrawState->fCoverageStages[s].localCoordChange(coordChangeMatrix);
     }
 }