Don't instantiate shaders with non-invertible local matrix

Change-Id: If11f7d57cbf45929632d858f91c02d8f5fa9f442
Reviewed-on: https://skia-review.googlesource.com/7885
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed