Revert of Remove gpu shader optimatization for solid white or trans black colors (https://codereview.chromium.org/375823005/)

Reason for revert:
possible test and gm failures

Original issue's description:
> Remove gpu shader optimatization for solid white or trans black colors
>
> Running test on the added bench which draws a grid of all white paths, all blue paths, or alternating checkered white/blue paths.
>
> With optimization in (ms):
>          White       Blue        Checkered
> Linux    ~80         ~80         ~160
> N7       ~800        ~1100       ~1500
> Moto-e   ~830        ~1100       ~2500
>
> Without optimization in (ms):
>          White       Blue        Checkered
> Linux    ~80         ~80         ~80
> N7       ~1100       ~1100       ~1100
> Moto-e   ~1100       ~1100       ~1500
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/5f78d2251a440443c9eaa321dad058d7a32bfef7

R=bsalomon@google.com
TBR=bsalomon@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Author: egdaniel@google.com

Review URL: https://codereview.chromium.org/385163004
diff --git a/src/gpu/gl/GrGLProgram.cpp b/src/gpu/gl/GrGLProgram.cpp
index 9e25a69..435d0cd 100644
--- a/src/gpu/gl/GrGLProgram.cpp
+++ b/src/gpu/gl/GrGLProgram.cpp
@@ -178,8 +178,12 @@
                 }
                 sharedState->fConstAttribColorIndex = -1;
                 break;
+            case GrGLProgramDesc::kSolidWhite_ColorInput:
+            case GrGLProgramDesc::kTransBlack_ColorInput:
+                sharedState->fConstAttribColorIndex = -1;
+                break;
             default:
-                SkFAIL("Unexpected color type.");
+                SkFAIL("Unknown color type.");
         }
     } else {
         sharedState->fConstAttribColorIndex = -1;
@@ -214,10 +218,11 @@
                 sharedState->fConstAttribCoverageIndex = -1;
                 break;
             case GrGLProgramDesc::kSolidWhite_ColorInput:
+            case GrGLProgramDesc::kTransBlack_ColorInput:
                 sharedState->fConstAttribCoverageIndex = -1;
                 break;
             default:
-                SkFAIL("Unexpected coverage type.");
+                SkFAIL("Unknown coverage type.");
         }
     } else {
         sharedState->fConstAttribCoverageIndex = -1;