make SkPath::conservativelyContainsRect consume degenerate segments

BUG=skia:

Change-Id: I3a39318bceaf6c95a50d84961d93af4ba62550e3
Reviewed-on: https://skia-review.googlesource.com/6900
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
2 files changed