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

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https://hg.mozilla.org/integration/gaia-central/rev/5838105aa22c
Author: Yoshi Huang <allstars.chh@mozilla.com>
Desc: Merge pull request #20283 from allstarschh/Bug1021213

Bug 1021213 - [B2G][NFC] The browser will remain in landscape mode after bumping with another NFC phone. r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/a09a73aa4d00
Author: Yoshi Huang <allstars.chh@mozilla.com>
Desc: Bug 1021213 - [B2G][NFC] The browser will remain in landscape mode after bumping with another NFC phone. r=alive
Bumping manifests a=b2g-bump