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

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https://hg.mozilla.org/integration/gaia-central/rev/a952b64a500c
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Merge pull request #12574 from viorelaioia/bug-922019

Bug 922019 - Fix broken progress locator for video app object

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https://hg.mozilla.org/integration/gaia-central/rev/a70b3f12e61e
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 922019 - Fix broken progress locator for video app object