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

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https://hg.mozilla.org/integration/gaia-central/rev/3f6d4ca21763
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #12918 from AndreiH/bug927817

Bug 927817 - test_clock_turn_on_off_alarm.py is getting a StaleElementEx...

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https://hg.mozilla.org/integration/gaia-central/rev/b36362119b38
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 927817 - test_clock_turn_on_off_alarm.py is getting a StaleElementException against desktopb2g