This point is located at fPoints[-1]. We might as well provide it
since it's free, and the stroke iterators for indirect tessellation
will be able to use it.
Bug: skia:10419
Change-Id: If0161a18a9a5a0f3b118a99d7c090d79d424f9db
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/337637
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>