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

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https://hg.mozilla.org/integration/gaia-central/rev/450445d485a8
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #15627 from huchengtw-moz/video/Bug_903253_nfc_sharing

Bug 903253 - [Gaia][Video] Video application: handle data transfer, r=gduan

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https://hg.mozilla.org/integration/gaia-central/rev/1270517adeee
Author: John Hu <johu@mozilla.com>
Desc: Bug 903253 - [Gaia][Video] Video application: handle data transfer
Bumping manifests a=b2g-bump