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

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https://hg.mozilla.org/integration/gaia-central/rev/d3955403d0bf
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #12727 from etiennesegonzac/bug-924233-dialer-part

Bug 924233 - Fixing a test failure when TelephonyHelperTest was run alone. r=Rik

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https://hg.mozilla.org/integration/gaia-central/rev/7e7124b8f7e5
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 924233 - Fixing a test failure when TelephonyHelperTest was run
alone.