[bug 978694] Tests for GraphiteMixin.
[bug 978694] Tests for GraphiteMixin.

This wasn't added to the original commit, too many untracked files.

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