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

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https://hg.mozilla.org/integration/gaia-central/rev/90e8c125510c
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #20126 from timdream/keyboard-dbltap-back

Bug 1020628 - Don't allow user to start activity twice in keyboard settings, r=rudyl

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https://hg.mozilla.org/integration/gaia-central/rev/5dfff84dcd1a
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 1020628 - Don't allow user to start activity twice in keyboard settings
Bumping manifests a=b2g-bump