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

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https://hg.mozilla.org/integration/gaia-central/rev/f6bdd9d219b8
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #13010 from staktrace/apzc-force-enable

Bug 929728 - Add a B2G developer settings option to enable APZC in all content processes. r=

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https://hg.mozilla.org/integration/gaia-central/rev/f2c4678b5f74
Author: Kartikaya Gupta <kgupta@mozilla.com>
Desc: Bug 929728 - Add a B2G developer settings option to enable APZ in all content processes. r=vingtetun