added DSL Modifiers

Change-Id: Ie1b0b8068b487905691b20e318c7898653763a25
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/359757
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
7 files changed