Detect an invalid intervalCount in SkRegion during deserialiation.

[Cherry-pick from 675576f023c8fa10cdb0c18bc0a6c214e0bab069 to M51 branch.]

TBR=robertphillips@google.com
BUG=609260
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1961463003

Original Review-Url: https://codereview.chromium.org/1961463003
NOTREECHECKS=true
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2027643002
1 file changed