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

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https://hg.mozilla.org/integration/gaia-central/rev/660836f801d2
Author: Dale  Harvey <dale@arandomurl.com>
Desc: Merge pull request #11735 from benfrancis/906055

Bug 906055 - Fix awesomescreen cache. r=daleharvey

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https://hg.mozilla.org/integration/gaia-central/rev/5256c8d533ff
Author: Ben Francis <ben@tola.me.uk>
Desc: Bug 906055 - Fix awesomescreen cache