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

========

https://hg.mozilla.org/integration/gaia-central/rev/4b2aa13b369b
Author: James Burke <jrburke@gmail.com>
Desc: Merge pull request #19217 from jrburke/bug1009900-email-compose-blue-line

Bug 1009900 - [email] blue focus line in compose r=mcav

========

https://hg.mozilla.org/integration/gaia-central/rev/2431c17b887d
Author: jrburke <jrburke@gmail.com>
Desc: Bug 1009900 - [email] blue focus line in compose

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "874cb76906782e01f6b861e6d957fd679b9a3778", 
+    "revision": "4b2aa13b369bcfd8e56222a002fff6a58287fa75", 
     "repo_path": "/integration/gaia-central"
 }