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

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https://hg.mozilla.org/integration/gaia-central/rev/c57af3afa7d2
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #10824 from alivedise/bugzilla/890753/homescreen-disapper-on-lockscreen-notification-callback

Bug 890753 - Use AppWindow setVisible on toggling homescreen app, r=timdream, a=leo+

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https://hg.mozilla.org/integration/gaia-central/rev/13fed8f150ac
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 890753 - Use AppWindow setVisible on toggling homescreen app
visibility