Check for element nodes.
The following construct(s) refer to this construct:
An ElementTest checks for an element node and its name and
can be of one of these forms:
element() and element(*) match any single
element node, regardless of its name or type.
element(QName) matches any
element node whose name is QName, regardless of its type.
The element test element(book) matches any element node
whose name is "book".
