Bug 757488 (livelist): Clone the NodeList before iterating
Bug 757488 (livelist): Clone the NodeList before iterating

NodeLists can be live, in which case _maybeImportNode can remove them from
the document, and thus the NodeList, which in turn breaks iteration.
So first we clone the list

mozilla/gcli,joewalker/gcli,joewalker/gcli,mozilla/gcli,mozilla/gcli