post apply non-scale transforms after imagefilters have run

may choose to eliminate the final matrix-filter buffer before the sprite blit, but at the moment want to defer that change to a 2nd CL.

heavily inspired by https://codereview.chromium.org/1140943004

Need these CLs to land first:
https://codereview.chromium.org/1898193005/#
https://codereview.chromium.org/1902253003/

BUG=skia:3288
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1899263002

Review URL: https://codereview.chromium.org/1899263002
4 files changed