Add minimal support for readPixels in raster F16

src/core/SkConfig8888.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkConfig8888.h"
@@ skipping 197 matching lines @@
     // If they agree on colorType and the alphaTypes are compatible, then we just memcpy.
     // Note: we've already taken care of 32bit colortypes above.
     if (srcInfo.colorType() == dstInfo.colorType()) {
         switch (srcInfo.colorType()) {
             case kRGB_565_SkColorType:
             case kAlpha_8_SkColorType:
             case kGray_8_SkColorType:
                 break;
             case kIndex_8_SkColorType:
             case kARGB_4444_SkColorType:
+            case kRGBA_F16_SkColorType:
                 if (srcInfo.alphaType() != dstInfo.alphaType()) {
                     return false;
                 }
                 break;
             default:
                 return false;
         }
         SkRectMemcpy(dstPixels, dstRB, srcPixels, srcRB, width * srcInfo.bytesPerPixel(), height);
         return true;
     }
@@ skipping 68 matching lines @@
         }
 
         SkPaint  paint;
         paint.setDither(true);
 
         canvas->clear(0);
         canvas->drawBitmap(bm, 0, 0, &paint);
         return true;
     }
 }