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

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https://hg.mozilla.org/integration/gaia-central/rev/85876a536a9a
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Merge pull request #16632 from eeejay/bug-976684

Bug 976684 - [Settings] Fix typo in screen reader start button label.

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https://hg.mozilla.org/integration/gaia-central/rev/825b9264f2ac
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 976684 - [Settings] Fix typo in screen reader start button label. r=kaze
Bumping manifests a=b2g-bump