* test/src/xml-tests.el (libxml-tests): Move half this test for the
recently obsoleted fourth argument to libxml-parse-xml-region...
* test/lisp/xml-tests.el (xml-tests--remove-comments): ...to a new
test here for xml-remove-comments.
* test/src/xml-tests.el (libxml-tests--data-comments-discarded):
Move test data from here...
* test/lisp/xml-tests.el (xml-tests--data-with-comments): ...to here.