2.2.10 [XML] Section 5.2, Using XML Processors


The specification states:

 The behavior of a validating XML processor is highly predictable; it must read 
 every piece of a document and report all well-formedness and validity violations. 
 Less is required of a non-validating processor; it need not read any part of the 
 document other than the document entity. ...

IE9 Mode, IE10 Mode, IE11 Mode, and EdgeHTML Mode (All Versions)

A non-validating XML parser is used.