Chromedriver: Make test runner emit proper test results

The chrome test result format needs failed tests to be marked as
unexpected to be recognized as true failures. Otherwise they're thought
to be acceptable failures, and don't show up as actual failures when
parsed.

Bug: 533481
Change-Id: Ica94a18a4503a5553ef5602627643ae526155e1a
Reviewed-on: https://chromium-review.googlesource.com/1109269Reviewed-by: John Chen <johnchen@chromium.org>
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569341}

chrome/test/chromedriver/test/run_py_tests.py

@@ -2884,6 +2884,7 @@ if __name__ == '__main__':
 
     for failure in result.failures + result.errors:
       output['tests'][failure[0].id()]['actual'] = 'FAIL'
+      output['tests'][failure[0].id()]['unexpected'] = True
 
     num_fails = len(result.failures) + len(result.errors)
     output['num_failures_by_type']['FAIL'] = num_fails