Preserve 'const' on globals and function parameters in runtime effects

Bug: skia:11716
Change-Id: Ic09071544b5b5216b01fbc9b478b6269dd96202f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/382280
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2 files changed