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

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https://hg.mozilla.org/integration/gaia-central/rev/336ec72b95eb
Author: Fabrice Desré <fabrice@desre.org>
Desc: Merge pull request #22795 from fabricedesre/app-eventhandler

Bug 1052618 - Prepare gaia to mozApps switching to webidl r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/851d1510da1b
Author: Fabrice Desré <fabrice@desre.org>
Desc: Bug 1052618 - Prepare gaia to mozApps switching to webidl r=kgrandon
Bumping manifests a=b2g-bump