Fix FF CI Failure
Fix FF CI Failure

Firefox was throwing an error when trying to alias 
the array.push method while other browsers were failing
silently.

R=benjamin.saller
CC=
https://codereview.appspot.com/12640043

bac/juju-gui,mitechie/juju-gui,mitechie/juju-gui,CanonicalJS/juju-gui,bac/juju-gui,mitechie/juju-gui,jrwren/juju-gui,mitechie/juju-gui,jrwren/juju-gui,bac/juju-gui,bac/juju-gui,jrwren/juju-gui,jrwren/juju-gui,CanonicalJS/juju-gui,CanonicalJS/juju-gui