[skif] Evaluate filters in layer's color type

Bug: skia:12979
Change-Id: I824f42fc8b4644fb707f93e5fc957eede7f8dfc2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/608716
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
3 files changed