Javadoc
Compile a topLevel() method into the output class. This method is
called from transform() to handle all non-template top-level elements.
Returns the signature of the topLevel() method.
Global variables/params and keys are first sorted to resolve
dependencies between them. The XSLT 1.0 spec does not allow a key
to depend on a variable. However, for compatibility with Xalan
interpretive, that type of dependency is allowed. Note also that
the buildKeys() method is still generated as it is used by the
LoadDocument class, but it no longer called from transform().