In recent runs of w3c-test-autoroller, it is now failing in the following way:

Stack trace:
.../update-w3c-test-expectations", line 13, in <module>
    sys.exit(line_adder.run())
.../webkitpy/w3c/update_w3c_test_expectations.py", line 50, in run
    test_expectations = self.get_expected_txt_files(test_expectations)
.../webkitpy/w3c/update_w3c_test_expectations.py", line 297, in get_expected_txt_files
    tests_to_rebaseline, tests_results = self.get_tests_to_rebaseline(tests, tests_results)
.../webkitpy/w3c/update_w3c_test_expectations.py", line 331, in get_tests_to_rebaseline
    if self.is_js_test(test) and tests_results.get(test_path):
.../webkitpy/w3c/update_w3c_test_expectations.py", line 341, in is_js_test
    return test_parser.is_jstest()
.../webkitpy/w3c/test_parser.py", line 135, in is_jstest
    return bool(self.test_doc.find(src=re.compile('[\'\"/]?/resources/testharness')))
AttributeError: 'NoneType' object has no attribute 'find'

Example build: https://build.chromium.org/p/chromium.infra.cron/builders/w3c-test-autoroller/builds/6957