validate indices for vertices

Bug: skia:7565
Change-Id: If5366cc0f5c9ce328376b9721b454b9160bf6764
Reviewed-on: https://skia-review.googlesource.com/102203
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
2 files changed