Add casting support to RP builder.

Change-Id: I7519c104b6d63d6e80b65e0d5a9fcecbdf65b93f
Bug: skia:13676
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/626036
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
2 files changed