handle clipping large triangles

originally found by fuzzer.

Bug: skia:
Change-Id: I45007a619f13936153c0db8a60b3631a2c9db20c
Reviewed-on: https://skia-review.googlesource.com/101741
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Mike Reed <reed@google.com>
3 files changed