Add support for glMemoryGlyphIndexArrayNV

Adds glMemoryGlyphIndexArrayNV to the GrGLInterface and begins
detecting support for this method in GrGLPathRendering.

BUG=skia:2939
Committed: https://skia.googlesource.com/skia/+/149b3ec2b1ccaf00e40bf296d2a3394852d73fe9

[Chris Dalton, 2014-09-12 22:18:07]

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

[Kimmo Kinnunen, 2014-09-15 07:59:17]

Btw: would it be useful for us to file a skia issue describing briefly how a
feature is planned to be implemented and when it is considered done?  Or would
this be redundant?

[bsalomon, 2014-09-15 14:06:11]

lgtm. WRT Kimmo's question: I think that'd be useful for us to track what you
guys are doing.

[Chris Dalton, 2014-09-16 06:45:51]

On 2014/09/15 14:06:11, bsalomon wrote:
> lgtm. WRT Kimmo's question: I think that'd be useful for us to track what you
> guys are doing.

Issue created here:

https://code.google.com/p/skia/issues/detail?id=2939&thanks=2939&ts=1410849875

Please let me know if you feel it is unclear or incomplete anywhere.

[Chris Dalton, 2014-09-16 22:21:08]

The CQ bit was checked by cdalton@nvidia.com

[commit-bot: I haz the power, 2014-09-16 22:22:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/570733002/1

[commit-bot: I haz the power, 2014-09-16 22:36:27]

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

[commit-bot: I haz the power, 2014-09-16 22:36:28]

Try jobs failed on following builders:
  Build-Win-VS2013-x86-Debug-Trybot on tryserver.skia
(http://108.170.220.76:10117/builders/Build-Win-VS2013-x86-Debug-Trybot/builds...)

[Chris Dalton, 2014-09-17 16:11:44]

The CQ bit was checked by cdalton@nvidia.com

[commit-bot: I haz the power, 2014-09-17 16:12:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/570733002/20001

[commit-bot: I haz the power, 2014-09-17 16:19:23]

Committed patchset #2 (id:20001) as 149b3ec2b1ccaf00e40bf296d2a3394852d73fe9