Make skpaint->grpaint flow work for composing draws

src/gpu/GrInvariantOutput.cpp

Index: src/gpu/GrInvariantOutput.cpp
diff --git a/src/gpu/GrInvariantOutput.cpp b/src/gpu/GrInvariantOutput.cpp
index 4c77df32f47fa3e74f8d873d8b6d130e9f37cd35..8de5817054e6b217ad2611041b787f1ed1d8794a 100644
--- a/src/gpu/GrInvariantOutput.cpp
+++ b/src/gpu/GrInvariantOutput.cpp
@@ -17,8 +17,6 @@ void GrInvariantOutput::validate() const {
         }
     }
 
-    SkASSERT(this->validPreMulColor());
-
     // If we claim that we are not using the input color we must not be modulating the input.
     SkASSERT(fNonMulStageFound || fWillUseInputColor);
 }
@@ -30,28 +28,5 @@ bool GrInvariantOutput::colorComponentsAllEqual() const {
            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