basic first pass at RGBA F32 support

Draws basically the same as f16.

The existing load_f32, load_f32_dst, and store_f32 stages all had the
same bug that we'd never noticed because dy was always 0 until now.

Change-Id: Ibbd393fa1acc5df414be4cdef0f5a9d11dcccdb3
Reviewed-on: https://skia-review.googlesource.com/137585
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index be3ebb1..b297f98 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -2871,6 +2871,7 @@
         case kRGB_565_SkColorType:
         case kN32_SkColorType:
         case kRGBA_F16_SkColorType:
+        case kRGBA_F32_SkColorType:
         case kRGBA_1010102_SkColorType:
             break;
         default: