SkSL sample() now permits specification of coordinates

Bug: skia:
Change-Id: I16073008ac852f1864bd1d2bd38087a5b661d05a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/232581
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
48 files changed