Make skpaint->grpaint flow work for composing draws

src/gpu/GrInvariantOutput.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrInvariantOutput.h"
 
 #ifdef SK_DEBUG
 
 void GrInvariantOutput::validate() const {
     if (fIsSingleComponent) {
         SkASSERT(0 == fValidFlags || kRGBA_GrColorComponentFlags == fValidFlags);
         if (kRGBA_GrColorComponentFlags == fValidFlags) {
             SkASSERT(this->colorComponentsAllEqual());
         }
     }
 
-    SkASSERT(this->validPreMulColor());
-
     // If we claim that we are not using the input color we must not be modulating the input.
     SkASSERT(fNonMulStageFound || fWillUseInputColor);
 }
 
 bool GrInvariantOutput::colorComponentsAllEqual() const {
     unsigned colorA = GrColorUnpackA(fColor);
     return(GrColorUnpackR(fColor) == colorA &&
            GrColorUnpackG(fColor) == colorA &&
            GrColorUnpackB(fColor) == colorA);
 }
 
-bool GrInvariantOutput::validPreMulColor() const {
-    if (kA_GrColorComponentFlag & fValidFlags) {
-        float c[4];
-        GrColorToRGBAFloat(fColor, c);
-        if (kR_GrColorComponentFlag & fValidFlags) {
-            if (c[0] > c[3]) {
-                return false;
-            }
-        }
-        if (kG_GrColorComponentFlag & fValidFlags) {
-            if (c[1] > c[3]) {
-                return false;
-            }
-        }
-        if (kB_GrColorComponentFlag & fValidFlags) {
-            if (c[2] > c[3]) {
-                return false;
-            }
-        }
-    }
-    return true;
-}
-
 #endif // end DEBUG