lots of sRGB and F16 blits

src/core/SkBlitter.cpp

Index: src/core/SkBlitter.cpp
diff --git a/src/core/SkBlitter.cpp b/src/core/SkBlitter.cpp
index a3dbe5e80fdeb1901f87f44769ec1037c807d04c..41d6071d6eb0581bc42bc0fab782659193158598 100644
--- a/src/core/SkBlitter.cpp
+++ b/src/core/SkBlitter.cpp
@@ -938,11 +938,13 @@ SkBlitter* SkBlitter::Choose(const SkPixmap& device,
             break;
 
         default:
-            SkDEBUGFAIL("unsupported device config");
-            blitter = allocator->createT<SkNullBlitter>();
             break;
     }
 
+    if (!blitter) {
+        blitter = allocator->createT<SkNullBlitter>();
+    }
+
     if (shader3D) {
         SkBlitter* innerBlitter = blitter;
         // innerBlitter was allocated by allocator, which will delete it.