Added type security checks to the DSL

Private / unsupported types are now restricted to module code.

Change-Id: I98cb2e0822560a274758d99ecf0ca09883d0c3a1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/445097
Reviewed-by: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
4 files changed