media rules implement nsIDOMCSSMediaRule. Fix insertRule() to be able to insert into the middle of a rule list. Fix issues with stylesheets not getting dirtied when media lists are modified. bug 93977, r=pierre, sr=jst git-svn-id: svn://10.0.0.236/trunk@102234 18797224-902f-48f8-a5cc-f745e15eee43