Replace dsl::Struct with StructDefinition::Convert.

Change-Id: Ic40cd45336a807b4dc7dbd59058945e83b5a3c24
Bug: skia:13821
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/697636
Commit-Queue: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
8 files changed