implement missing blends

Change-Id: Ie8a02d1906fbd43b9975d29b8cd0e00409f0f1d4
Reviewed-on: https://skia-review.googlesource.com/c/174802
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
2 files changed