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

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https://hg.mozilla.org/integration/gaia-central/rev/3e924f3b2ffe
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #14610 from crdlc/bug-948934

Bug 948934 - [Download Manager] The downloading icon is not displayed du...

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https://hg.mozilla.org/integration/gaia-central/rev/285ad848f079
Author: crdlc <crdlc@tid.es>
Desc: Bug 948934 - [Download Manager] The downloading icon is not displayed during the download