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

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https://hg.mozilla.org/integration/gaia-central/rev/b9ca53fe9549
Author: Rex KM Lee <rexboy@mozilla.com>
Desc: Merge pull request #13165 from rexboy7/fix-bug930944

Bug 930944 - [System] Don't turn screen off after poweroff animation

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https://hg.mozilla.org/integration/gaia-central/rev/9add16ac90f3
Author: Rex Lee <rexboy@mozilla.com>
Desc: Bug 930944 - [System] Don't turn screen off after poweroff animation