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

Tools/Scripts/webkitpy/style/error_handlers_unittest.py

 # Copyright (C) 2010 Chris Jerdonek (cjerdonek@webkit.org)
 #
 # 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 APPLE INC. AND ITS 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 APPLE INC. OR ITS 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 tests for error_handlers.py."""
 
-
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from checker import StyleProcessorConfiguration
 from error_handlers import DefaultStyleErrorHandler
 from filter import FilterConfiguration
 
 
 class DefaultStyleErrorHandlerTest(unittest.TestCase):
 
     """Tests the DefaultStyleErrorHandler class."""
 
@@ skipping 150 matching lines @@
                           ["foo.h(50):  message  [whitespace/tab] [5]\n"])
 
         # Error on non-modified line after turning off line filtering: error.
         error_handler.turn_off_line_filtering()
         self._call_error_handler(error_handler, confidence, line_number=60)
         self.assertEqual(2, self._error_count)
         self.assertEqual(self._error_messages,
                           ['foo.h(50):  message  [whitespace/tab] [5]\n',
                            'foo.h(60):  message  [whitespace/tab] [5]\n',
                            'Suppressing further [whitespace/tab] reports for this file.\n'])