Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_4/rev/99fd2dbe8e41
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #18664 from timdream/keyboard-settings

Bug 988782 - Allow keyboard settings page manages it's own life, r=rudyl
Bumping manifests a=b2g-bump