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/6c086c3c8c1a
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #12992 from gaye/bug-920261

Bug 920261 - mailto links broken r=jrburke(cherry picked from commit 5387ea6411c669a262de0914f6a196055449c5b9)

Conflicts:
	apps/browser/test/marionette/share_url_test.js