Add tests of the runtime effect stage factories

We were testing this with .rtcf and .rts files, but those don't go
through the MakeForXXX factories. This would have caught the bug fixed
in https://skia-review.googlesource.com/c/skia/+/398229

Change-Id: Id824e7bf32982c043978b2981cfd91dd7a9b2585
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/398183
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
1 file changed