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

Tools/Scripts/webkitpy/common/system/platforminfo_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:
 #
 #    * 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 platform
 import sys
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from webkitpy.common.system.executive import Executive
 from webkitpy.common.system.executive_mock import MockExecutive, MockExecutive2
 from webkitpy.common.system.platforminfo import PlatformInfo
 
 
 def fake_sys(platform_str='darwin', windows_version_tuple=None):
 
     class FakeSysModule(object):
         platform = platform_str
@@ skipping 129 matching lines @@
         self.assertEqual(info.total_bytes_memory(), 1234)
 
         info = self.make_info(fake_sys('win32', tuple([6, 1, 7600])))
         self.assertIsNone(info.total_bytes_memory())
 
         info = self.make_info(fake_sys('linux2'))
         self.assertIsNone(info.total_bytes_memory())
 
         info = self.make_info(fake_sys('freebsd9'))
         self.assertIsNone(info.total_bytes_memory())