Modify Adreno 3xx workaround to toggle face culling rather than call glFlush.

This fixes some correctness issues introduced by the previous workaround in MSAA gm images. It hopefully improves performance regressions introduced in MSAA benchmarks from calling glFlush.

A comment on the workaround is updated to indicate that the original line-drop-out bug was seen on the N5 running driver 127.0. It simply showed up in different GMs that on the N7 running 127.0

Bug: skia:6755
Change-Id: Ief066fd9b223c043a80e7fe07ff13aac07a48970
Reviewed-on: https://skia-review.googlesource.com/19481
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
3 files changed