Append a content node to the end of the child list. This method handles calling BindToTree on the child appropriately.
the content to append
whether to notify the document (current document for nsIContent, and |this| for nsIDocument) that the append has occurred
if one attempts to have more than one element node as a child of a document. Doing this will also assert -- you shouldn't be doing it! Check with nsIDocument::GetRootContent() first if you're not sure. Apart from this one constraint, this doesn't do any checking on whether aKid is a valid child of |this|.