SkRegion: change serialization unit tests, better validation code

Also: Don't alloc before validation.

Change-Id: Ic2e007ecf4e06fb099366295b963f66df3f7903a
Reviewed-on: https://skia-review.googlesource.com/8728
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
2 files changed