This addresses (hopefully) all of the remaining suboptimal positions in
SkSL error reporting.
Change-Id: I5bc977b03d51153b841a89fa687e54e3e9cb6ec3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/527976
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>