Rewrite GrQuad to use separate arrays of x and y values to be Sk4f friendly.

Change-Id: Ie2ad197c5f17849fe6e034b60bc7ec18a00edb24
Reviewed-on: https://skia-review.googlesource.com/128842
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
9 files changed