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

========

https://hg.mozilla.org/integration/gaia-central/rev/3d4209fdf720
Author: Dave Hunt <dave.hunt@gmail.com>
Desc: Bug 909839 - Merge JavaScript 'atoms' used by gaia and gaiatest. r=jgriffin r=zcampbell

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "3451eb6b72d2de8045179163c42e84d6519ad86d", 
+    "revision": "3d4209fdf7201bf36c64e21f96d9c4b8b1b3a347", 
     "repo_path": "/integration/gaia-central"
 }