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

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https://hg.mozilla.org/integration/gaia-central/rev/8534d14f0ff0
Author: Jan Jongboom <janjongboom@gmail.com>
Desc: Merge pull request #12748 from comoyo/new_ime_webidl3

Bug 906096 - Switch InputMethod to WebIDL in IME tests and FF Nightly. r=RudyL

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https://hg.mozilla.org/integration/gaia-central/rev/3cce48619d4d
Author: Jan Jongboom <janjongboom@gmail.com>
Desc: Bug 906096 - Switch InputMethod to WebIDL in IME tests and FF Nightly