Added DSL layout() support

Change-Id: I698dd607ff4676b6fb29be0a718c6073b66dc7c7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/406336
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
6 files changed