Use new path::iter

- also add assert when accessing conicWeight()

Change-Id: I093da54fa80b92ee41f00f81ac7a8b45102afc47
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1035518
Reviewed-by: Florin Malita <fmalita@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Mike Reed <mike@reedtribe.org>
15 files changed