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

Tools/Scripts/webkitpy/common/lru_cache_unittest.py

 # Copyright (C) 2011 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
 # in the documentation and/or other materials provided with the
 # distribution.
 
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # 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 webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from webkitpy.common import lru_cache
 
 
 class LRUCacheTest(unittest.TestCase):
 
     def setUp(self):
         self.lru = lru_cache.LRUCache(3)
         self.lru['key_1'] = 'item_1'
         self.lru['key_2'] = 'item_2'
@@ skipping 46 matching lines @@
 
     def test_get_middle_item(self):
         self.lru['key_2']
         self.lru['key_4'] = 'item_4'
         self.lru['key_5'] = 'item_5'
         self.assertEqual(set(self.lru.keys()), set(['key_2', 'key_4', 'key_5']))
 
     def test_set_again(self):
         self.lru['key_1'] = 'item_4'
         self.assertEqual(set(self.lru.items()), set([('key_1', 'item_4'), ('key_3', 'item_3'), ('key_2', 'item_2')]))