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

Tools/Scripts/webkitpy/layout_tests/models/test_failures_unittest.py

 # Copyright (C) 2010 Google Inc. All rights reserved.
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 #    * Redistributions of source code must retain the above copyright
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 # this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from webkitpy.layout_tests.models.test_failures import *
 
 
 class TestFailuresTest(unittest.TestCase):
     def assert_loads(self, cls):
         failure_obj = cls()
         s = failure_obj.dumps()
         new_failure_obj = TestFailure.loads(s)
         self.assertIsInstance(new_failure_obj, cls)
@@ skipping 24 matching lines @@
         self.assertNotEqual(FailureCrash(), FailureTimeout())
         crash_set = set([FailureCrash(), FailureCrash()])
         self.assertEqual(len(crash_set), 1)
         # The hash happens to be the name of the class, but sets still work:
         crash_set = set([FailureCrash(), "FailureCrash"])
         self.assertEqual(len(crash_set), 2)
 
     def test_crashes(self):
         self.assertEqual(FailureCrash().message(), 'content_shell crashed')
         self.assertEqual(FailureCrash(process_name='foo', pid=1234).message(), 'foo crashed [pid=1234]')