`@!has` (and `@!matches`) with two arguments used to treat the second
argument as a literal string of HTML code. Now, that feature has been
renamed into `@!hasraw` (and `@!matchesraw`), and the arity-2 `@!has`
version is an error.
These uses thought the second argument was being treated as an XPath, as
with the arity-3 version, but in fact was being treated as literal HTML.
Because these were checking for the *absence* of the string, the tests
silently did nothing -- an XPath string won't ever be showing up in the
test's generated HTML!
