Remove unused imports in webkitpy with using autoflake.

third_party/WebKit/Tools/Scripts/webkitpy/performance_tests/perftestsrunner_unittest.py

 # Copyright (C) 2012 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 595 matching lines @@
         output_json_path = runner._output_json_path()
 
         filesystem.write_text_file(output_json_path, '[{"previous": "results"}]')
 
         self._test_run_with_json_output(runner, port.host.filesystem)
 
         self.assertEqual(self._load_output_json(runner), [{
             "buildTime": "2013-02-08T15:19:37.460000", "tests": self._event_target_wrapper_and_inspector_results,
             "revisions": {"chromium": {"timestamp": "2013-02-01 08:48:05 +0000", "revision": "5678"}}}])
         self.assertTrue(filesystem.isfile(filesystem.splitext(output_json_path)[0] + '.html'))
-        pass
 
     def test_run_generates_and_show_results_page(self):
         runner, port = self.create_runner_and_setup_results_template(args=['--output-json-path=/mock-checkout/output.json'])
         page_shown = []
         port.show_results_html_file = lambda path: page_shown.append(path)
         filesystem = port.host.filesystem
         self._test_run_with_json_output(runner, filesystem, results_shown=False)
 
         expected_entry = {"buildTime": "2013-02-08T15:19:37.460000",
                           "tests": self._event_target_wrapper_and_inspector_results,
@@ skipping 145 matching lines @@
         self._test_run_with_json_output(runner, port.host.filesystem, compare_logs=False)
         generated_json = json.loads(port.host.filesystem.files['/mock-checkout/output.json'])
         self.assertTrue(isinstance(generated_json, list))
         self.assertEqual(len(generated_json), 1)
 
         output = generated_json[0]['tests']['Bindings']['tests']['event-target-wrapper']['metrics']['Time']['current']
         self.assertEqual(len(output), 3)
         expectedMetrics = EventTargetWrapperTestData.results['metrics']['Time']['current'][0]
         for metrics in output:
             self.assertEqual(metrics, expectedMetrics)