Loosen requirements for mixed samples support

Loosen requirements for mixed samples support

Quits requiring EXT_raster_multisample and
NV_sample_mask_override_coverage for mixed samples support. This will
allow platforms without those latter extensions (i.e. Chrome) to still
use mixed samples for path rendering. Also moves the mixed samples cap
out of shader caps, since it no longer denotes shader functionality.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/63f6c1fc5b04fb154151f521c97a549060141374

[Chris Dalton, 2015-11-05 18:50:00]

cdalton@nvidia.com changed reviewers:
+ bsalomon@google.com, egdaniel@google.com, kkinnunen@nvidia.com

[Chris Dalton, 2015-11-05 18:50:01]

Leaving in the EXT_raster_multisample API, we will add caps for it in the
future.

[egdaniel, 2015-11-05 20:50:57]

lgtm

[Chris Dalton, 2015-11-06 02:59:42]

I'll let this sit until tommorrow in case Kimmo has any comments.

[Kimmo Kinnunen, 2015-11-06 07:38:10]

On 2015/11/06 02:59:42, Chris Dalton wrote:
> I'll let this sit until tommorrow in case Kimmo has any comments.

yay

[Kimmo Kinnunen, 2015-11-06 07:41:33]

On 2015/11/06 07:38:10, Kimmo Kinnunen wrote:
> On 2015/11/06 02:59:42, Chris Dalton wrote:
> > I'll let this sit until tommorrow in case Kimmo has any comments.
> 
> yay

though, RasterSamples is now a function that is not governed by any cap, so it
is even more dead code.

[Chris Dalton, 2015-11-06 14:47:11]

On 2015/11/06 07:41:33, Kimmo Kinnunen wrote:
> On 2015/11/06 07:38:10, Kimmo Kinnunen wrote:
> > On 2015/11/06 02:59:42, Chris Dalton wrote:
> > > I'll let this sit until tommorrow in case Kimmo has any comments.
> > 
> > yay
> 
> though, RasterSamples is now a function that is not governed by any cap, so it
> is even more dead code.

That's right. I have a change on the way (today hopefully?) That will put it
back under a cap.

[Chris Dalton, 2015-11-06 14:47:15]

The CQ bit was checked by cdalton@nvidia.com

[commit-bot: I haz the power, 2015-11-06 14:47:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1410383011/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1410383011/1

[commit-bot: I haz the power, 2015-11-06 14:48:16]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-11-06 14:48:17]

Try jobs failed on following builders:
  skia_presubmit-Trybot on client.skia.fyi (JOB_FAILED,
http://build.chromium.org/p/client.skia.fyi/builders/skia_presubmit-Trybot/bu...)

[bsalomon, 2015-11-06 15:08:29]

On 2015/11/06 14:48:17, commit-bot: I haz the power wrote:
> Try jobs failed on following builders:
>   skia_presubmit-Trybot on client.skia.fyi (JOB_FAILED,
>
http://build.chromium.org/p/client.skia.fyi/builders/skia_presubmit-Trybot/bu...)

lgtm

[Chris Dalton, 2015-11-06 15:09:02]

The CQ bit was checked by cdalton@nvidia.com

[commit-bot: I haz the power, 2015-11-06 15:09:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1410383011/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1410383011/1

[commit-bot: I haz the power, 2015-11-06 15:09:46]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/63f6c1fc5b04fb154151f521c97a549060141374