Add SkSL DSLType

Change-Id: I0bbda6a41391fc2a11dc812be5e9c0c0d14c4d75
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/351921
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
9 files changed