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

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https://hg.mozilla.org/integration/gaia-central/rev/5c300229820f
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #12219 from alivedise/bugzilla/912796_v2

Bug 912796 - Back to main screen when attention screen is shown

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https://hg.mozilla.org/integration/gaia-central/rev/abed136ad3d5
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 912796 - Back to main screen when attention screen is shown