[graphite] Account for primitive blending depending on dst

Bug: b/280052759
Change-Id: I5cd2776893f0ec02b0f39869921ebc86a2abbb11
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/696478
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: James Godfrey-Kittle <jamesgk@google.com>
3 files changed