Add convenience overload of SkPointPriv::SetRectTriStrip that takes SkRect

Change-Id: Idf5bfafaf19c20f074f12d706b8b8984c5935e6d
Reviewed-on: https://skia-review.googlesource.com/129185
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
7 files changed