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

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https://hg.mozilla.org/integration/gaia-central/rev/ef355aa8244d
Author: Ben Kelly <bkelly@mozilla.com>
Desc: Merge pull request #13007 from wanderview/contacts-webidl-delete

Bug 929287: Only create mozContact if we don't already have one.  r=arcturus

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https://hg.mozilla.org/integration/gaia-central/rev/d94603ee4bf7
Author: Ben Kelly <ben@wanderview.com>
Desc: Bug 929287: Only create mozContact if we don't already have one.