Remove thirdparty/unittest2 from webkitpy and require python2.7.

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 14 matching lines @@
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 """Unit tests for run_perf_tests."""
 
 import StringIO
 import datetime
 import json
 import re
-import unittest2 as unittest
+import unittest
 
 from webkitpy.common.host_mock import MockHost
 from webkitpy.common.system.outputcapture import OutputCapture
 from webkitpy.layout_tests.port.driver import DriverOutput
 from webkitpy.layout_tests.port.test import TestPort
 from webkitpy.performance_tests.perftest import ChromiumStylePerfTest
 from webkitpy.performance_tests.perftest import DEFAULT_TEST_RUNNER_COUNT
 from webkitpy.performance_tests.perftest import PerfTest
 from webkitpy.performance_tests.perftestsrunner import PerfTestsRunner
 
@@ skipping 708 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)