fold matrices together for tricolor

Bug: skia:
Change-Id: Ic4ef679c6b5514f0fc7f895d71b5feeb812da53e
Reviewed-on: https://skia-review.googlesource.com/16606
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed