security checks in the XBL code (so that all the security checks are gated through LoadBindingDocumentInfo). Bug 204140, r=dbaron for the CSS changes, r=sicking for the XBL changes, sr=sicking. In particular, this change allows user stylesheets loaded from local files to link to local files. git-svn-id: svn://10.0.0.236/trunk@230242 18797224-902f-48f8-a5cc-f745e15eee43