Support function calls in SkSL-to-SkVM

Bug: skia:10680
Change-Id: I8697bdc157d250f3c390c7f49074318aa8c7bdab
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/351918
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
3 files changed