Record concat as setMatrix.

Mainly this cuts out a type to have to think about in SkRecord world.
It also means all the CTMs are recorded directly in the SkRecord, so
we can track the current CTM by pointer rather than by copying.

BUG=skia:
R=reed@google.com, mtklein@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/484673003
3 files changed