Preserve triangle winding in GrTessellator

Ensures the tessellator's triangles always wind in the same direction
as if the path had been triangulated as a simple fan (a la red book).

Change-Id: I1275a6dc9c2673e5f710ca46c357409dcd233162
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263390
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Stephen White <senorblanco@chromium.org>
2 files changed