Move from SkChunkAlloc to SkArenaAlloc for PathOps

Attempt two. Remove ~SkOpContour because it is handled by the SkArenaAlloc.

Change-Id: Id3049db97aebcc1009d403a031f2fac219f58f2f
Reviewed-on: https://skia-review.googlesource.com/9381
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Herb Derby <herb@google.com>
15 files changed