fix fuzz assert

Recent rewrite of SkPath::isConvexity() introduced a debugging
assert while fuzzing. The convexity computed by a proper cross product
may be zero while the short-cut cross product is zero or one.

This debugging code was added to make sure that the short cut was
correctly implemented and matched the regular code, but otherwise
isn't that important to maintain (now that it works). For now,
try fixing the assert to allow the full cross product to return zero
(e.g., if it underflows). If this shows up again, probably correct
just to delete or comment out the debugging code check.

R=kjlubick@google.com

Bug: skia:
Change-Id: If3f772432852f9e325789185cd283466af837a05
Reviewed-on: https://skia-review.googlesource.com/c/177896
Commit-Queue: Cary Clark <caryclark@skia.org>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Auto-Submit: Cary Clark <caryclark@skia.org>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
1 file changed