We do not claim any compatibility with (or accept patches / bug reports for) Alpha, Beta or Canary releases of browsers.
(L1) support for the latest and greatest browser available from the Chrome release channel.
(L1) support for the latest and greatest browser available from the Firefox release channel.
(L2) support for ESR releases.
(L1) support for IE11
(L2) support for IE9 and IE10
Specific OS versions?
(L1) support for v6 and v7 on Mac
Others (Opera etc)