Add caching of ambient and spot shadow meshes.

Change-Id: If882186225621af4af4b4ddae0c786ec33ff40f3
Reviewed-on: https://skia-review.googlesource.com/7643
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
2 files changed