Indexing into a constant matrix is a constant expression, so we are
obligated to support it for ES2 compatibility.
Change-Id: Ibe1e5bac39d9a88ce0222997a38e8b6952fdb336
Bug: skia:12472
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/469819
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
6fae052362