Bumping gaia.json for 1 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/3dc8e8f9f7d5
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #13462 from timdream/keyboard-callback-error

Bug 935868 - check for callback(), r=rudyl