never check for degenerates in path::iter

This does not appear to be used externally, and only internally in 3
sites in GPU, which we can handle explicitly.

For now you can still pass bools to Iter::next() but they are ignored.
After this lands, I will update the callers to remove those.

FWIW: none of our other tests or gms seem to notice this change...

Bug: skia:9339
Change-Id: If40077b1ebb3d47cfce0ec43996ff272318e4a62
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/235104
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Mike Reed <reed@google.com>
20 files changed