Disable tonal color for shadowutils GMs

Change-Id: Id64ad0cdf1378d38940cfe0d8335ce4d5776abd2
Reviewed-on: https://skia-review.googlesource.com/74361
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
1 file changed