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

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https://hg.mozilla.org/integration/gaia-central/rev/c8b2d242ca99
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #13006 from alivedise/bugzilla/929285/soft-home-height

Bug 929285 - Predefine appWindow height with software home button enable...r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/e08038e3d5ef
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 929285 - Predefine appWindow height with software home button enabled