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

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https://hg.mozilla.org/integration/gaia-central/rev/4712354decf4
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #22170 from azasypkin/bug-1042887-scroll-messages

Bug 1042887 - Cannot scroll in messages app. Removed redundant "composer-messages-container". r=julien

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https://hg.mozilla.org/integration/gaia-central/rev/0bc48e44da6b
Author: Aleh Zasypkin <azasypkin@mozilla.com>
Desc: Bug 1042887 - Cannot scroll in messages app. Removed redundant "composer-messages-container". r=julien
Bumping manifests a=b2g-bump