remove legacy virtual for vertices, only support object form

BUG=skia:6366

Change-Id: Ic422fa44a788d3488c050c6218dbfba188bb8f3e
Reviewed-on: https://skia-review.googlesource.com/9835
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
29 files changed