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

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https://hg.mozilla.org/integration/gaia-central/rev/3458b7608383
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #9203 from pivanov/bug-844615

Bug 844615 - Email Layout and Font Revisions - New Account (All done screen) | follow-up patch

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https://hg.mozilla.org/integration/gaia-central/rev/302a1cdb7c60
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 844615 - Email Layout and Font Revisions - New Account (All done screen) | follow-up patch