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

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https://hg.mozilla.org/integration/gaia-central/rev/70a2c51fbe37
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #12538 from huchengtw-moz/video/Bug_921421_move_to_start_while_ending

Bug 921421 - [Video] pause the video and back to beginning when a video ..., r=djf

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https://hg.mozilla.org/integration/gaia-central/rev/231b1c2ddfc8
Author: John Hu <johu@mozilla.com>
Desc: Bug 921421 - [Video] pause the video and back to beginning when a video plays to end