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

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https://hg.mozilla.org/integration/gaia-central/rev/fe641115270a
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #22704 from timdream/hardwarebuttons-testfix

Bug 999605 - Fix intermittent error in HardwareButtons tests, r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/90a600244943
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 999605 - Fix intermittent error in HardwareButtons tests
Bumping manifests a=b2g-bump