Our documentation for webkit_user_style_sheet_new says: "URI patterns must be of the form [protocol]://[host]/[path], where the *host* and *path* components can contain the wildcard character (*) to represent zero or more other characters." But looking at UserContentURLPattern.cpp, that's not right. Either the entire host must be * (match all domains) or the host must begin with *. (match all subdomains); any other use of * in the host string is invalid. This was reported on IRC by the Midori folks.
See bugs #112476 and #37931