Fast path translate() in SkCanvas and SkLiteDL.

This adds didTranslate() so that SkLiteDL (and other canvas recorders)
can record the translate rather than the full concat.

It also adds a case to SkMatrix::preTranslate() to fast path
translate x translate -> translate (i.e. +=).

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2255283002

Review-Url: https://codereview.chromium.org/2255283002
7 files changed