Fix issues with insetting and outsetting quads.

Need more degrees of freedom when moving 3D points to project to 2D
points that don't fall on the projected quad edges.

Need to check geometry subset in shader to avoid positive coverage in
outset quads with nearly parallel edges.

Bug: chromium:1177833
Change-Id: I0759382d9221ba44aacd537254e08d9f2716a6af
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/372196
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
4 files changed