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

Tools/Scripts/webkitpy/layout_tests/port/base_unittest.py

 # Copyright (C) 2010 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 12 matching lines @@
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # 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.
 
 import logging
 import optparse
 import sys
 import tempfile
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from webkitpy.common.system.executive import Executive, ScriptError
 from webkitpy.common.system import executive_mock
 from webkitpy.common.system.filesystem_mock import MockFileSystem
 from webkitpy.common.system.outputcapture import OutputCapture
 from webkitpy.common.system.path import abspath_to_uri
 from webkitpy.thirdparty.mock import Mock
 from webkitpy.tool.mocktool import MockOptions
 from webkitpy.common.system.executive_mock import MockExecutive, MockExecutive2
 from webkitpy.common.system.systemhost_mock import MockSystemHost
@@ skipping 417 matching lines @@
         suite = VirtualTestSuite('suite/bar', 'base/foo', ['--args'])
         self.assertFalse(hasattr(suite, 'name'))
         self.assertFalse(hasattr(suite, 'base'))
         self.assertFalse(hasattr(suite, 'args'))
 
     def test_legacy(self):
         suite = VirtualTestSuite('suite/bar', 'base/foo', ['--args'], use_legacy_naming=True)
         self.assertEqual(suite.name, 'virtual/suite/bar')
         self.assertEqual(suite.base, 'base/foo')
         self.assertEqual(suite.args, ['--args'])