start working on tiger again

The tiger tests are a suite under development
that exercise many coincident edge cases.

This fixes the case when a duplicate point is not
ignored when the coincident span references the
primary point.

TBR=reed@google.com
BUG=skia:5131
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2239803002

Review-Url: https://codereview.chromium.org/2239803002
4 files changed