Minimize computeTotalInverse()'s inputs


The helper doesn't need a full context rec - it only looks at the CTM
and external local matrix.  Pass these explicitly instead.
Change-Id: I6a5884f65cd383c2df0e8d83c9086789bd96f345
Reviewed-on: https://skia-review.googlesource.com/15870
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
4 files changed