GrTessellator: convert contours to VertexLists.

This is a cleanup patch; should have no user-visible effects.

Note that contours are now returned opened, rather than closed. This
plays better with VertexList, and makes the code simpler.

BUG=skia:

Change-Id: I6a422fed0805cdca53cf0697b8427fff7cd77ad3
Reviewed-on: https://skia-review.googlesource.com/9343
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
1 file changed