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

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https://hg.mozilla.org/integration/gaia-central/rev/634ce13613a2
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #16915 from julienw/979990-fix-xfail-list

Bug 979990 - Fix xfail.list order r=rik

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https://hg.mozilla.org/integration/gaia-central/rev/b6578244fce7
Author: Julien Wajsberg <felash@gmail.com>
Desc: Bug 979990 - Fix xfail.list order r=rik
Bumping manifests a=b2g-bump