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

Tools/Scripts/webkitpy/style/checkers/text_unittest.py

 # Copyright (C) 2009 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.
 
 """Unit test for text_style.py."""
 
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 import text as text_style
 from text import TextChecker
 
 class TextStyleTestCase(unittest.TestCase):
     """TestCase for text_style.py"""
 
     def assertNoError(self, lines):
         """Asserts that the specified lines has no errors."""
         self.had_error = False
@@ skipping 38 matching lines @@
     """Tests TextChecker class."""
 
     def mock_handle_style_error(self):
         pass
 
     def test_init(self):
         """Test __init__ constructor."""
         checker = TextChecker("foo.txt", self.mock_handle_style_error)
         self.assertEqual(checker.file_path, "foo.txt")
         self.assertEqual(checker.handle_style_error, self.mock_handle_style_error)