give up on quad root if infinite

SkPath::contains() uses SkFindUnitQuadRoots to see
which side of a curve a point is on. If the
intermediate exceeds a float, return no found root.

R=reed@google.com
BUG=572406
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1556353002

Review URL: https://codereview.chromium.org/1556353002
NOTREECHECKS=true
NOTRY=true
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1580463002