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

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https://hg.mozilla.org/integration/gaia-central/rev/a4f1842f7bd5
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15334 from KevinGrandon/bug_959867_task_manager_focus

Bug 959867 - [Rocketbar] Input should be focused if empty task manager r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/370df8e6f537
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 959867 - [Rocketbar] Input should be focused if empty task manager r=alive