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

Tools/Scripts/webkitpy/style/checkers/xcodeproj_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:
 # 1.  Redistributions of source code must retain the above copyright
 #     notice, this list of conditions and the following disclaimer.
 # 2.  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.
 
 """Unit test for xcodeproj.py."""
+import unittest
 
 import xcodeproj
-import webkitpy.thirdparty.unittest2 as unittest
 
 
 class TestErrorHandler(object):
     """Error handler for XcodeProjectFileChecker unittests"""
     def __init__(self, handler):
         self.handler = handler
 
     def turn_off_line_filtering(self):
         pass
 
@@ skipping 22 matching lines @@
         error_handler = TestErrorHandler(handler)
         checker = xcodeproj.XcodeProjectFileChecker('', error_handler)
         checker.check(lines)
         self.assertTrue(self.had_error, '%s should have error: %s.' % (lines, expected_message))
 
     def test_detect_development_region(self):
         self.assert_no_error(['developmentRegion = English;'])
         self.assert_error([''], 'Missing "developmentRegion = English".')
         self.assert_error(['developmentRegion = Japanese;'],
                           'developmentRegion is not English.')