"support" 3D masks like Ganesh does

Ignore the mul and add planes and just use the A8 mask.
It's better than not drawing anything at all.

Change-Id: Ic20cec975c2db5c7aeb46ab7b430e8442dc8d8e9
Reviewed-on: https://skia-review.googlesource.com/71440
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed