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

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https://hg.mozilla.org/integration/gaia-1_4/rev/aa489be6dd8b
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Merge pull request #18390 from mcav/icon-repeated

Bug 992876 - Reply icon repeated. r=jrburke
Conflicts:
	apps/email/js/cards/message_reader.html
Bumping manifests a=b2g-bump