Enable WebVR for LayoutTests

Enable WebVR during layout testing.

The primary motivation at this time is to make sure that WebVR
does not introduce any regression in other parts of the software.

BUG=389343
Committed: https://crrev.com/36bd4b148293adc0b4ba169b7dfb789d65f3f516
Cr-Commit-Position: refs/heads/master@{#353530}

[lgombos, 2015-10-11 17:49:50]

l.gombos@samsung.com changed reviewers:
+ bajones@chromium.org

[lgombos, 2015-10-11 17:53:39]

Brandon, what do you think ? 

This would help catching issues like this much earlier -
https://codereview.chromium.org/1398523002 and make sure we WebVR does not
regress other functionality.

This would also allow us to start adding LayoutTests for WebVR.

This change does not impact any of the stable or dev chrome/chromium builds.

[bajones, 2015-10-11 22:05:45]

I think this is a great precautionary measure. Thank you! LGTM.

[lgombos, 2015-10-12 02:20:43]

l.gombos@samsung.com changed reviewers:
+ jochen@chromium.org

[lgombos, 2015-10-12 02:20:44]

jochen@chromium.org: Please review changes in 

RuntimeEnabledFeatures.in

This will only impact what we test and not what we ship.

[jochen (gone - plz use gerrit), 2015-10-12 11:03:57]

lgtm

[lgombos, 2015-10-12 13:38:21]

The CQ bit was checked by l.gombos@samsung.com

[commit-bot: I haz the power, 2015-10-12 13:38:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1391323003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1391323003/40001

[commit-bot: I haz the power, 2015-10-12 15:29:51]

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

[commit-bot: I haz the power, 2015-10-12 15:29:51]

Exceeded global retry quota

[lgombos, 2015-10-12 16:14:30]

The CQ bit was checked by l.gombos@samsung.com

[commit-bot: I haz the power, 2015-10-12 16:15:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1391323003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1391323003/40001

[commit-bot: I haz the power, 2015-10-12 16:22:46]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-10-12 16:24:18]

Patchset 3 (id:??) landed as
https://crrev.com/36bd4b148293adc0b4ba169b7dfb789d65f3f516
Cr-Commit-Position: refs/heads/master@{#353530}