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

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https://hg.mozilla.org/integration/gaia-central/rev/eeb604fca314
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #10778 from gasolin/master-881141

Bug 881141 - hdpi/xhdpi resolution assets and layout for Usage app, r=salva

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https://hg.mozilla.org/integration/gaia-central/rev/89c376aa6e4e
Author: gasolin <gasolin@gmail.com>
Desc: Bug 881141 - hdpi/xhdpi resolution assets and layout for Usage app