Fix some bugs with read/writePixels

- On both GL and Vulkan, we must draw if writing to an MSAA surface.
  Otherwise we just write to the resolve target texture, which gets
  overwritten on the next resolve.
- On Vulkan, we must draw if the target isn't a texture. (This check
  was already present in onWritePixels).
- On Vulkan, when reading from an MSAA surface as a different config,
  we don't need the readConfig to be renderable with MSAA - the temp
  surface is always created non-MSAA.

- Added tests for these fixes, verified that they failed previously.

Bug: skia:
Change-Id: Ia2d5025d7a8f8de8630413453f83b58028dd41aa
Reviewed-on: https://skia-review.googlesource.com/13691
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
4 files changed