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

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https://hg.mozilla.org/integration/gaia-central/rev/4bb4d3d734ee
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Merge pull request #24646 from evanxd/bug-1071988

Bug 1071988 - Include date_time_helper.js. r=mcav

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https://hg.mozilla.org/integration/gaia-central/rev/5452abf3886c
Author: Evan Xd <itoyxd@gmail.com>
Desc: Bug 1071988 - Include date_time_helper.js
Bumping manifests a=b2g-bump