deal more consistently with unsortable edges

Improve line/curve coincident detection and resolution. This fixed the remaining simple failures.

When an edge is unsortable, use the ray intersection to determine the angles' winding.

Deal with degenerate segments.

TBR=reed@google.com
BUG=skia:3588,skia:3762

Review URL: https://codereview.chromium.org/1140813002
14 files changed