Add test using 'fragmentProcessor' in runtime effects

Allowed today, will soon be an error.

Bug: skia:11813
Change-Id: I5c13de7657fa85f13fa6d80e1d890225d8a3e868
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/392439
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
3 files changed