Revert of remove workaround for dx9 angle slow rgba pixel ops

include/gpu/gl/GrGLConfig.h

Index: include/gpu/gl/GrGLConfig.h
diff --git a/include/gpu/gl/GrGLConfig.h b/include/gpu/gl/GrGLConfig.h
index 665ebedf22cceab3adfbe4e3348f6e1d113e59ad..93d5b395cb812bf5e5e439246258c863fcb956eb 100644
--- a/include/gpu/gl/GrGLConfig.h
+++ b/include/gpu/gl/GrGLConfig.h
@@ -65,6 +65,10 @@
  * The GrGLInterface field fCallback specifies the function ptr and there is an
  * additional field fCallbackData of type intptr_t for client data.
  *
+ * GR_GL_RGBA_8888_PIXEL_OPS_SLOW: Set this to 1 if it is known that performing
+ * glReadPixels / glTex(Sub)Image with format=GL_RGBA, type=GL_UNISIGNED_BYTE is
+ * significantly slower than format=GL_BGRA, type=GL_UNISIGNED_BYTE.
+ *
  * GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL: Set this to 1 if calling
  * glReadPixels to read the entire framebuffer is faster than calling it with
  * the same sized rectangle but with a framebuffer bound that is larger than
@@ -124,6 +128,10 @@
     #define GR_GL_PER_GL_FUNC_CALLBACK                  0
 #endif
 
+#if !defined(GR_GL_RGBA_8888_PIXEL_OPS_SLOW)
+    #define GR_GL_RGBA_8888_PIXEL_OPS_SLOW              0
+#endif
+
 #if !defined(GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL)
     #define GR_GL_FULL_READPIXELS_FASTER_THAN_PARTIAL   0
 #endif