Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/7a8f719c4824
Author: Zbigniew Braniecki <gandalf@mozilla.com>
Desc: Bug 1052136 - follow up fix to a unit test that regressed. r=me
Bumping manifests a=b2g-bump