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

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https://hg.mozilla.org/integration/gaia-central/rev/849ffc9bd7ff
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Merge pull request #18339 from kumarrishav/issue-980402

Bug 980402 - Remove navigator.mozMobileConnection uses from the homescreen app / everything.me r=crdlc

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https://hg.mozilla.org/integration/gaia-central/rev/713b91b6b7d6
Author: kumarrishav <rishav006@gmail.com>
Desc: Bug 980402 - Remove navigator.mozMobileConnection uses from the homescreen app / everything.me
Bumping manifests a=b2g-bump