remove workaround for dx9 angle slow rgba pixel ops

src/gpu/GrGpu.h

Index: src/gpu/GrGpu.h
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index 3bb84a448586b6d563b1cbddf6b9ca115802ad1e..d9c2e18bdb1070548500de3484ab8060886c29b6 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -148,8 +148,7 @@ public:
     }
 
     /**
-     * Called before uploading writing pixels to a GrTexture when the src pixel config doesn't
-     * match the texture's config.
+     * Called before uploading writing pixels to a GrTexture.
      */
     virtual bool canWriteTexturePixels(const GrTexture*, GrPixelConfig srcConfig) const = 0;