Fix most unit tests and the conformance test runner.

I found the "unit" tests to be tremendously helpful while building [pyjsonselect](https://github.com/danvk/pyjsonselect).

Most of them were broken. This PR doesn't fix all of them, but it does fix most:

`parse_test.html`: 1 tests of 26 passed, 25 failed. → 21 tests of 26 passed, 5 failed. _(+20 passes!)_
`lex_test.html`: 21 tests of 28 passed, 7 failed. _(unchanged)_
`match_test.html`: 13 tests of 13 passed, 0 failed.  _(unchanged)_
`conformance_test.html`: JavaScript error on page → 47 tests of 47 passed, 0 failed. _(+47 passes!)_