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

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https://hg.mozilla.org/integration/gaia-1_4/rev/b57d7f8d29cf
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #19856 from RudyLu/keyboard/Bug1013570_commit

Bug 1013570 - [B2G][Keyboard]Double or triple tapping on the spacebar.
r=timdream.
(cherry picked from commit f0a8ab7d0b6000cc2c2cd2a201964bafa959858b)

Conflicts:
	apps/keyboard/js/imes/latin/latin.js
	apps/keyboard/js/keyboard.js
	apps/keyboard/js/keyboard/input_method_manager.js
Bumping manifests a=b2g-bump