nsIDocumentEncoderNodeFixup in Firefox 3.6a1pre

 Create a fixed up version of a node. This method is called before
 each node in a document is about to be persisted. The implementor
 may return a new node with fixed up attributes or null. If null is
 returned the node should be used as-is.
 @param aNode Node to fixup.
 @param [OUT] aSerializeCloneKids True if the document encoder should
 apply recursive serialization to the children of the fixed up node
 instead of the children of the original node.
 @return The resulting fixed up node.