Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/74d7c4e578b1
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #24885 from pivanov/bug-1078174

Bug 1078174 - [Contact] Improve UI on contact settings

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https://hg.mozilla.org/integration/gaia-central/rev/2e6aca22423c
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 1078174 - [Contact] Improve UI on contact settings

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "6a306f592d986b5064e72bac0e76315ff8e4fcfd", 
+    "revision": "74d7c4e578b12815bf43d5955b0168fe090dd82c", 
     "repo_path": "integration/gaia-central"
 }