Make SkShadowUtils tessellations ref counted in preparation for caching them.

Change-Id: I60133fcc4101a27bcc3e7ad38e7348ad9147b8a9
Reviewed-on: https://skia-review.googlesource.com/7784
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
4 files changed