More SkOffsetSimplePolygon optimizations.

* Count edges and prealloc array
* Use first offset for reflex testing rather than recomputing
* Construct list pointers in edge setup array

Bug: skia:
Change-Id: I61a2a6de28a419157c6dad997b0dde0a7999b89e
Reviewed-on: https://skia-review.googlesource.com/145372
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
1 file changed