Fix most unit tests and the conformance test runner.

[danvk]

I found the "unit" tests to be tremendously helpful while building 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!)

[lambdalabdesigner]

Review status: 0 of 3 files reviewed at latest revision, 1 unresolved discussion.

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src/test/parse_test.html, line 86 at r1 (raw file):

h-last-child(-3n - 3)");

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