Review and support Firefox 15
https://developer.mozilla.org/en/Firefox_15_for_developers http://beta.elchi3.de/doctracker/#list=fx&version=15.0
From the dev doc, my major concern at a glance is the high resolution timers. WebSMS also looks bad for mobile. I have not yet gone through the undocumented bugs.
Also, lots of patch conflicts this time: 8, 10, 11, 14, and 17-21.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information