fix hanging fuzz in AsWinding

R=kjlubick@google.com

Bug: skia:
Change-Id: Ib34e3d4716887b63fe465de3f20c27e74ec46467
Reviewed-on: https://skia-review.googlesource.com/c/161543
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Cary Clark <caryclark@skia.org>
1 file changed