some fuzzer fixes

should fix three or four of the PathOp asserts
triggered by the fuzzer tool.

R=kjlubick@google.com
Bug: skia:
Change-Id: I470895addf1e922da6a7c41d44d54eca92e68fb6
Reviewed-on: https://skia-review.googlesource.com/113163
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Cary Clark <caryclark@skia.org>
11 files changed