For example, from google:
My guess is this might be somehow related to framing.
However, it uses:
webHost : window.location.hostname
which in theory should work even in a framing scenario, unless the context of the JavaScript was somehow lost. On http://jsfiddle.net/596mX/ the top web host is htp://jsfiddle.net, the frame host is http://fiddle.jshell.net, and it alerts the latter's hostname.
Version: unspecified
Severity: normal
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=55449