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

Tools/Scripts/webkitpy/style/checker_unittest.py

 # -*- coding: utf-8; -*-
 #
 # Copyright (C) 2009 Google Inc. All rights reserved.
 # Copyright (C) 2009 Torch Mobile Inc.
 # Copyright (C) 2009 Apple Inc. All rights reserved.
 # Copyright (C) 2010 Chris Jerdonek (chris.jerdonek@gmail.com)
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
@@ skipping 17 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.
 
 """Unit tests for style.py."""
 
 import logging
 import os
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 import checker as style
 from webkitpy.common.system.logtesting import LogTesting, TestLogStream
 from checker import _BASE_FILTER_RULES
 from checker import _MAX_REPORTS_PER_CATEGORY
 from checker import _PATH_RULES_SPECIFIER as PATH_RULES_SPECIFIER
 from checker import _all_categories
 from checker import check_webkit_style_configuration
 from checker import check_webkit_style_parser
 from checker import configure_logging
@@ skipping 760 matching lines @@
         """Test that carriage returns aren't stripped from files that are allowed to contain them."""
         file_path = 'carriage_returns_allowed.txt'
         lines = ['line1\r', 'line2\r']
         line_numbers = [100]
         self._processor.process(lines=lines,
                                 file_path=file_path,
                                 line_numbers=line_numbers)
         # The carriage return checker should never have been invoked, and so
         # should not have saved off any lines.
         self.assertFalse(hasattr(self.carriage_checker, 'lines'))