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

Tools/Scripts/webkitpy/style/checkers/test_expectations_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 10 matching lines @@
 # 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 os
 import sys
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from test_expectations import TestExpectationsChecker
 from webkitpy.common.host_mock import MockHost
 
 
 class ErrorCollector(object):
     """An error handler class for unit tests."""
 
     def __init__(self):
         self._errors = []
@@ skipping 50 matching lines @@
         self.assertFalse(self._error_collector.turned_off_filtering)
 
     def test_valid_expectations(self):
         self.assert_lines_lint(["crbug.com/1234 [ Mac ] passes/text.html [ Pass Failure ]"], should_pass=True)
 
     def test_invalid_expectations(self):
         self.assert_lines_lint(["Bug(me) passes/text.html [ Give Up]"], should_pass=False)
 
     def test_tab(self):
         self.assert_lines_lint(["\twebkit.org/b/1 passes/text.html [ Pass ]"], should_pass=False, expected_output="Line contains tab character.  [whitespace/tab] [5]")