Bumping gaia.json for 3 gaia-central revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/dc22cb96998e
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Merge pull request #13368 from eeejay/bug-920839

Bug 920839 - Value Selector accessibility improvements. r=timdream

========

https://hg.mozilla.org/integration/gaia-central/rev/1a2ebd989db0
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 920839 - Added spinbutton ARIA markup to value picker.

========

https://hg.mozilla.org/integration/gaia-central/rev/1cff0273e0b1
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 920839 - ARIA fixes to value selector.