Add triangle support to GrPathOuterCurveTessellator

Supports drawing exact triangles as conics with infinite weight. This
is necessary for drawing inner fans, breadcrumb triangles, and extra
triangles that will be introduced when we start splitting curves that
don't fit in a single patch.

Bug: skia:10419
Change-Id: If72560be4eb38340512be55dccea93b3a083fad5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/410836
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
7 files changed