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

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https://hg.mozilla.org/integration/gaia-central/rev/489cfed0f404
Author: AndreiH <andrei.hutusoru@gmail.com>
Desc: Merge pull request #15464 from viorelaioia/bug_961039

Bug 961039 - Xfail test_cost_control_data_alert_mobile

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https://hg.mozilla.org/integration/gaia-central/rev/4f74510bfefc
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 961039 - Xfail test_cost_control_data_alert_mobile
Bumping manifests a=b2g-bump