Reland "draw vertices: put SkVM implementation behind a flag"

This is a reland of 2efda3ad1699e0590aa52c090ce02c82417da801

I don't know what I was thinking. I forgot to run tests
with --skvm. I think it needs to follow back on Raster
Pipeline until I have drawVertices fully implemented for
SkVM.

Original change's description:
> draw vertices: put SkVM implementation behind a flag
>
> Change-Id: I8bcaad6169d5e243b48984657347efed7063b654
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/433496
> Commit-Queue: Herb Derby <herb@google.com>
> Reviewed-by: Mike Reed <reed@google.com>

Change-Id: I5d5e16e7a1f4e3ff008a3d095556b6bf9ed19073
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/433980
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Herb Derby <herb@google.com>
1 file changed