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

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https://hg.mozilla.org/integration/gaia-central/rev/2d758b78e9b7
Author: Rex KM Lee <rexboy@mozilla.com>
Desc: Merge pull request #11751 from rexboy7/fix-bug900838

bug 900838 - [System] play poweron video after first repaint

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https://hg.mozilla.org/integration/gaia-central/rev/c00c087b7bb6
Author: Rex Lee <rexboy@mozilla.com>
Desc: bug 900838: [System] play poweron video after first repaint