Bug 3811

Steps to reproduce: 1) Load an XML document that uses namespaces. In particular, there should be an xml:lang attribute. 2) Add some namespaced stuff to the DOM tree using the NS-aware DOM level 2 API calls. 3) Use the setAttributeNS and setAttribute methods to attempt to modify the xml:lang attribute. 4) POST the modified doc to the server. Actual results: The serialization does not have namespaces at all and the local names are used as element and attribute names. The element that had an xml:lang attribute may now have two (!) attributes named lang making the serialization ill-formed! Expected results: Expected a namespace-savvy serializer to be used. That is, expected the serializer to preserve (ns-URI,localName) pairs by synthetizing xmlns attibutes and prefixes if necessary. Expected residual prefixes and xmlns attributes to be used as hints of preferred prefixes when possible. Expected DOM Level 1 tampering with the xml:foo attributes to get the namespace right. (IE does not do namespaces or DOM Level 1 but does have sane behavior with DOM Level 1 and xml:foo attributes.) Additional info: I had to fall back to RSS-style non-XML-ish language metadata, which is uncool.