[skrive] Rectangle support

... plus assorted fixes

TBR=
Change-Id: Idd4432eecd910b79e25418cef6247888ec1ade5d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299283
Commit-Queue: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
15 files changed