remove kA1_Config, as it is no longer supported

src/core/SkBlitter.cpp

Index: src/core/SkBlitter.cpp
diff --git a/src/core/SkBlitter.cpp b/src/core/SkBlitter.cpp
index dc7946a4bdefd64e2ed0b43b681673ce84f7abc7..9682d5572a97c3c245c7d381d6a535a6eb97a8d8 100644
--- a/src/core/SkBlitter.cpp
+++ b/src/core/SkBlitter.cpp
@@ -945,11 +945,6 @@ SkBlitter* SkBlitter::Choose(const SkBitmap& device,
 
 
     switch (device.config()) {
-        case SkBitmap::kA1_Config:
-            SK_PLACEMENT_NEW_ARGS(blitter, SkA1_Blitter,
-                                  storage, storageSize, (device, *paint));
-            break;
-
         case SkBitmap::kA8_Config:
             if (drawCoverage) {
                 SkASSERT(NULL == shader);