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

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https://hg.mozilla.org/integration/gaia-central/rev/a4d472efb940
Author: punamdahiya <punamdahiya@yahoo.com>
Desc: Merge pull request #12717 from punamdahiya/Bug924170_Video_Marionette_Tests

Bug924170 - [Video] - Add Marionette tests for Video App r=jugglinmike

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https://hg.mozilla.org/integration/gaia-central/rev/ecc458fabefe
Author: Punam Dahiya <punamdahiya@yahoo.com>
Desc: Bug924170 - [Video] - Add Marionette tests for Video App r=jugglinmike