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

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https://hg.mozilla.org/integration/gaia-central/rev/b577f4f387cc
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #11477 from gasolin/tabhomemq

Bug 903915 - [Flatfish][Homescreen] add support for large device, r=crdlc

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https://hg.mozilla.org/integration/gaia-central/rev/687497ce9d94
Author: gasolin <gasolin@gmail.com>
Desc: Bug 903915 - [Flatfish][Homescreen] add support for large device