Revert of Enable stencil clipping in mixed sampled render targets (patchset #6 id:100001 of https:/…

Revert of Enable stencil clipping in mixed sampled render targets (patchset #6 id:100001 of https://codereview.chromium.org/1232103002/ )

Reason for revert:
Co-centered sample locations are not needed to do stencil clip with mixed samples

Original issue's description:
> Implement stencil clipping in mixed sampled render targets
>
> This change enables multisampled clipping for mixed sampled
> render targets.  Previously clipping in mixed samples config
> behaved the same as in the gpu config.
>
> In order to retrofit non-MSAA draw methods, programmable sample
> locations are used in order to colocate all samples at (0.5, 0.5).
> Requires support for NV_sample_locations.
>
> BUG=skia:4399
>
> Committed:
> https://skia.googlesource.com/skia/+/3e77ba96d56d15db30ac6d8ccb900e30aafcbb16

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/7e806f3f8a542bb6b2026a843de99a8640e2e87f

[Chris Dalton, 2015-11-10 22:20:45]

cdalton@nvidia.com changed reviewers:
+ bsalomon@google.com

[bsalomon, 2015-11-11 20:00:53]

lgtm

[Chris Dalton, 2015-11-11 23:04:13]

The CQ bit was checked by cdalton@nvidia.com

[commit-bot: I haz the power, 2015-11-11 23:04:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415873011/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415873011/1

[commit-bot: I haz the power, 2015-11-11 23:16:10]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/7e806f3f8a542bb6b2026a843de99a8640e2e87f