another batch of lowp stages

The 4444 image in all_bitmap_configs now draws slightly different before
and after serialization.  (It's serialized as 8888.)  Still looks fine.

Change-Id: I1396cf1550b6769a1734ed25d59bd5b1866dfacd
Reviewed-on: https://skia-review.googlesource.com/65960
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
19 files changed