Remove assert from SkStroke.cpp

If we can't trust the contains tests on the bounding boxes we're already in a bad place.
With this change we'll somewhat arbitrarily get one of the two contours but, hopefully,
given the degeneracy of the geometry it won't matter which one dominates.

BUG=skia:6491
Change-Id: Id6f92f9331dc04a2555267781b07e5218345ef1b
Reviewed-on: https://skia-review.googlesource.com/103460
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
2 files changed