Implement caching of stroked paths in the tessellating path renderer.

This requires adding the stroke info to the cache key, and doing the
stroking and dashing before rendering as triangles.

BUG=skia:3755

Committed: https://skia.googlesource.com/skia/+/29e0d3f267a03546f236023347cdb4595ece2fd1

Review URL: https://codereview.chromium.org/1275553002
3 files changed