XMLParser ignores spec in type check

[rbouckaert]

If an XML element is referred before its declaration in the file, and the element has a reserved name (like parameter, tree) and the element has a spec attribute, the object is created at the time the idref is parsed. At the time the element's parent is parsed, the type is derived from the element name, and the spec attribute is ignored. This leads to a (supposedly helpful) type-check failing, and the XML parser throwing an exception, while there is nothing wrong.
To fix this, the spec element (if present) should not be ignored at the time the element is parsed at the point the its parent is parsed.