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

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https://hg.mozilla.org/integration/gaia-central/rev/830f6fa9313c
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #16047 from flodolo/bug968778

Bug 968778 - [browser] "Cancel" is hard-coded in the dialog appearing when long tapping on a link r=benfrancis

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https://hg.mozilla.org/integration/gaia-central/rev/399daa196b4f
Author: Francesco Lodolo (:flod) <flod@lodolo.net>
Desc: Bug 968778 - [browser] "Cancel" is hard-coded in the dialog appearing when long tapping on a link
Bumping manifests a=b2g-bump