Make GrSimpleMeshDrawOpHelper consider blend barriers/dst textures for batching.

Change-Id: Idc6f924e39a08da9fb4b441a72c4d9caa76b0fe0
Reviewed-on: https://skia-review.googlesource.com/15312
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
5 files changed