[graphite] Actually detect Transform type and scale factors

Bug: skia:12787
Change-Id: I5d061d535878df55ce57add7d0831e86caadc321
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/524009
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
3 files changed