Use kLow_SkFilterQuality when generating shader masks

This prevents edge aliasing for kDecal tiling.

Change-Id: I3a66e49ec1900bbe19c6700ec2f766122af4a3ce
Reviewed-on: https://skia-review.googlesource.com/113124
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
1 file changed