remove unused VerticesFlags

Deferring removing the flags parameter from the virtuals until a
later CL (as it collides with another related CL)

BUG=skia:6366

Change-Id: I817fae3df03ecebe5ec3532f691ed06deab890e6
Reviewed-on: https://skia-review.googlesource.com/9739
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Mike Reed <reed@google.com>
10 files changed