https://bugzilla.mozilla.org/show_bug.cgi?id=568375
568375 - SpiderMonkey never generates JSOP_XMLOBJECT bytecode
RESOLVED (jimb) in Core - JavaScript Engine. Last updated 2010-07-14.
spidermonkeyneverjsopbytecode
https://cwiki.apache.org/confluence/display/XMLBEANS/XmlObject
XmlObject - XMLBEANS - Apache Software Foundation
apachesoftwarefoundation