[fix bug 899554] Adding style to hide back to top button by default.
[fix bug 899554] Adding style to hide back to top button by default.

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