Skip bad line segments inside gen_alpha_deltas

Bug: chromium:847386
Change-Id: I5bb3268c27ecfbd66268adbc36be3ea72e0a69ba
Reviewed-on: https://skia-review.googlesource.com/131324
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>
Auto-Submit: Yuqian Li <liyuqian@google.com>
1 file changed