We were replacing points with the intersection of opposite edges.
Because of the distance tolerance we're using that may fall outside
of the original quad. Detect those cases and use averages of
intersection points instead.
Bug: chromium:1167277
Change-Id: I36b172f19339839bb21c060ddfe8109c184e9327
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/356311
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
