In runtime effects, verify that loops conform to ES2 rules

Bug: skia:11094
Change-Id: I68a08e79d29579901b74daca3c22f5112fbb3c8c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/353356
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
13 files changed