More shadow tessellation cleanup.

This change removes a lot of the unnecessary code that managed
coincident and collinear vertices and set the winding direction.
It also merges duplicate code when adding edges.

Bug: skia:7971
Change-Id: I0397db93c1075e332c5aeb9ca0343bcbd9bb70eb
Reviewed-on: https://skia-review.googlesource.com/133580
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
1 file changed