Fixed UB in SkSL constant arithmetic

Change-Id: Ic6da9f043a6657added5f9a3d1fed919043db9e0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/286436
Auto-Submit: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed