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

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https://hg.mozilla.org/integration/gaia-central/rev/6848389ae79d
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #14670 from julienw/947977-fix-scroll-when-typing

Bug 947977 - [Messages] Bug 936370 regressed the scrolling behavior when...

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https://hg.mozilla.org/integration/gaia-central/rev/36d8420457e5
Author: Julien Wajsberg <felash@gmail.com>
Desc: Bug 947977 - [Messages] Bug 936370 regressed the scrolling behavior when redacting a multi-line message r=schung