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

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https://hg.mozilla.org/integration/gaia-central/rev/099b2936d78a
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #12987 from wanderview/uitest-webidl-enable

Bug 929078: Re-enable gaia-ui-tests hidden for webidl bustage.

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https://hg.mozilla.org/integration/gaia-central/rev/fa604769d2a7
Author: Ben Kelly <ben@wanderview.com>
Desc: Bug 929078: Re-enable gaia-ui-tests hidden for webidl bustage.