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

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https://hg.mozilla.org/integration/gaia-central/rev/609bdd846144
Author: Fabrice Desré <fabrice@desre.org>
Desc: Merge pull request #12797 from fabricedesre/bug924032

Bug 924032 - ~40ms delay from app.launch to mozChromeEvent r=vingtetun

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https://hg.mozilla.org/integration/gaia-central/rev/3d7323c1105f
Author: Fabrice Desré <fabrice@desre.org>
Desc: Bug 924032 - ~40ms delay from app.launch to mozChromeEvent r=vingtetun