Remove remaining unused imports in webkitpy.

third_party/WebKit/Tools/Scripts/webkitpy/common/system/path_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 12 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.
 
 import sys
 import unittest
 
 from webkitpy.common.system.systemhost import SystemHost
-from webkitpy.common.system.platforminfo import PlatformInfo
 from webkitpy.common.system.platforminfo_mock import MockPlatformInfo
 from webkitpy.common.system import path
 
 
 class AbspathTest(unittest.TestCase):
 
     def platforminfo(self):
         return SystemHost().platform
 
     def test_abspath_to_uri_cygwin(self):
@@ skipping 29 matching lines @@
 
         # Call cygpath to ensure the subprocess is running.
         path.cygpath("/cygdrive/c/foo.txt")
         self.assertTrue(path._CygPath._singleton.is_running())
 
         # Stop it.
         path._CygPath.stop_cygpath_subprocess()
 
         # Ensure that it is stopped.
         self.assertFalse(path._CygPath._singleton.is_running())