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

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https://hg.mozilla.org/integration/gaia-central/rev/bd415987c213
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Merge pull request #23021 from cctuan/1054126

Bug 1054126 - Support "fullscreen_layout" field in manifest

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https://hg.mozilla.org/integration/gaia-central/rev/312694fc83fb
Author: cctuan <georgeiscoming@gmail.com>
Desc: Bug 1054126 - Support fullscreen_layout field in manifest
Bumping manifests a=b2g-bump