1) Add a RemoveChild() method to nsIWebshell. 2) nsWebshell::Destroy() calls this method on its parent to remove itself from the parent's child list. 3) Call nsWebshell::Destroy() from nsHTMLFrameInnerFrame's detructor. git-svn-id: svn://10.0.0.236/trunk@30304 18797224-902f-48f8-a5cc-f745e15eee43