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

========

https://hg.mozilla.org/integration/gaia-central/rev/a0459d28e262
Author: Dale Harvey <dale@arandomurl.com>
Desc: Bug 946445 - preventDefault when we handle the context menu. r=benfrancis

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "5ef0c4bb4ffac2061946e1c8462df1d27def60f4", 
+    "revision": "a0459d28e2621d13656694988effb4576506064c", 
     "repo_path": "/integration/gaia-central"
 }