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

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https://hg.mozilla.org/integration/gaia-central/rev/f4e8293a9534
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #12616 from teodosia/xfail-play-youtube-video

Bug 922936 - Xfail test_play_youtube_video due to bug 922334 r=zac

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https://hg.mozilla.org/integration/gaia-central/rev/a6b88b013ebf
Author: Teodosia Pop <teodosia.pop@gmail.com>
Desc: Bug 922936 - Xfail test_play_youtube_video due to bug 922334