This will help us write tests confirming that runtime blends work the
same as the built-in blends.
Change-Id: I2f94aa7bbbc7124d09b490fc7509a4c281025307
Bug: skia:12080
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/427618
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
