Revert "Revert "remove kA1_Config, as it is no longer supported""

src/effects/SkTransparentShader.cpp

Index: src/effects/SkTransparentShader.cpp
diff --git a/src/effects/SkTransparentShader.cpp b/src/effects/SkTransparentShader.cpp
index 970e74faa80f41364e599e492bb685587cb4117e..1d7e80877e169f41612121cd1306c498427fd2b7 100644
--- a/src/effects/SkTransparentShader.cpp
+++ b/src/effects/SkTransparentShader.cpp
@@ -94,9 +94,6 @@ void SkTransparentShader::shadeSpan(int x, int y, SkPMColor span[], int count) {
             }
             break;
         }
-        case SkBitmap::kA1_Config:
-            SkDEBUGFAIL("kA1_Config umimplemented at this time");
-            break;
         default:    // to avoid warnings
             break;
     }