Bumping gaia.json for 3 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/5b2c9b6b5072
Author: Dave Hunt <dave.hunt@gmail.com>
Desc: Bug 946644 - Fix skip-if syntax issue for emulators. r=jgriffin

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https://hg.mozilla.org/integration/gaia-central/rev/f6b7ecfe1912
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Merge pull request #14468 from Rik/contact-in-dialer-fake-943779

Bug 943779 - Need to update the images displayed while the contact tab i... r=etienne

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https://hg.mozilla.org/integration/gaia-central/rev/8619c01678bb
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Bug 943779 - Need to update the images displayed while the contact tab is loading with the new visuals