Bumping gaia.json for 3 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/2166c60b5eb1
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #13874 from jmcanterafonseca/fb_favs_link_img

Bug 937205 - [B2G][Contacts] Contact picture does not display after Link...
(cherry picked from commit f55c9746b9ae4a1aab739d6015ebff3cf51d21f3)

Conflicts:
	apps/communications/contacts/js/fb_resolver.js

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https://hg.mozilla.org/integration/gaia-1_2/rev/f6272f911721
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Merge pull request #13834 from AndreiH/gecko_prefs_v1.2

Bug 932750 - Add helper methods to GaiaData to get and set Gecko prefs

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https://hg.mozilla.org/integration/gaia-1_2/rev/99f029220601
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 932750 - Add helper methods to GaiaData to get and set Gecko prefs