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

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https://hg.mozilla.org/integration/gaia-central/rev/e824d612071f
Author: Ben Kelly <bkelly@mozilla.com>
Desc: Merge pull request #12318 from wanderview/contacts-css-opt-2

Bug 918174: Load CSS from contacts index.html  r=jmcf

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https://hg.mozilla.org/integration/gaia-central/rev/2388edbb9f0c
Author: Ben Kelly <ben@wanderview.com>
Desc: Bug 918174: Load CSS from contacts index.html