better matrix 3x3 invert

I didn't think hard about this... just folded through constants.

Change-Id: I994773009964e183691cf5f10861756acfe4b2ae
Reviewed-on: https://skia-review.googlesource.com/118986
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed