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

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https://hg.mozilla.org/integration/gaia-central/rev/6158d6cdc08f
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #22410 from mnils/Bug-1047126

Bug 1047126 - Keyboard transition should not overlap the soft home key bar, r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/3aeee74d5038
Author: Markus Nilsson <markus.nilsson@sonymobile.com>
Desc: Bug 1047126

Keyboard transition should not overlap the soft home key bar.
Bumping manifests a=b2g-bump