Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/f42e47a5c154
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #18386 from gurumukhi/patch-12

Bug 973484 - Remove workaround of bug 783076, r=timdream

========

https://hg.mozilla.org/integration/gaia-central/rev/cd1eee4a801c
Author: Ram Dayal Vaishnav <vaishnav.rd@gmail.com>
Desc: Bug 973484 - Remove workaround of bug 783076
Bumping manifests a=b2g-bump