[bug 886968] Use SessionStorage for Messages.
[bug 886968] Use SessionStorage for Messages.

ChristineLaMuse/mozillians,johngian/mozillians,chirilo/mozillians,akarki15/mozillians,hoosteeno/mozillians,safwanrahman/mozillians,hoosteeno/mozillians,safwanrahman/mozillians,brian-yang/mozillians,safwanrahman/mozillians,chirilo/mozillians,brian-yang/mozillians,fxa90id/mozillians,hoosteeno/mozillians,akarki15/mozillians,johngian/mozillians,mozilla/mozillians,justinpotts/mozillians,ChristineLaMuse/mozillians,johngian/mozillians,akatsoulas/mozillians,brian-yang/mozillians,akatsoulas/mozillians,akatsoulas/mozillians,fxa90id/mozillians,chirilo/mozillians,mozilla/mozillians,anistark/mozillians,mozilla/mozillians,justinpotts/mozillians,akatsoulas/mozillians,fxa90id/mozillians,johngian/mozillians,hoosteeno/mozillians,anistark/mozillians,mozilla/mozillians,akarki15/mozillians,fxa90id/mozillians,anistark/mozillians,brian-yang/mozillians,justinpotts/mozillians,akarki15/mozillians,chirilo/mozillians,safwanrahman/mozillians,anistark/mozillians,ChristineLaMuse/mozillians,justinpotts/mozillians