Rather than intersecting outset edge equations we outset each vertex
half a pixel along its two adjacent edges.
This approach will allow for water tight seams along shared edges
when we allow a subset of the quad edges to be antialiased.
Bug: skia:
Change-Id: I7f36ea658cc84dfcf364b138ec382bb709c278df
Reviewed-on: https://skia-review.googlesource.com/156742
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
42e086cd2d