Use the unswapped end point y for early out case in winding_line

The x-coordinates are not swapped, so using the swapped y will result
in a comparison with the wrong (end) point.

BUG=skia:4265
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1533873002

Review URL: https://codereview.chromium.org/1533873002
2 files changed