fix tiger b

The tiger tests have uncovered numerous bugs.
This CL fixes the last of them.

If a pair of curves do not intersect, but
have one or both ends very close to the opposite
curve, consider that an intersection.

TBR=reed@google.com
BUG=skia:5131
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2356363003

Review-Url: https://codereview.chromium.org/2356363003
13 files changed