Remove remaining unused imports in webkitpy.

third_party/WebKit/Tools/Scripts/webkitpy/common/system/stack_utils_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 11 matching lines @@
 # 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 sys
 import unittest
 
-from webkitpy.common.system import outputcapture
 from webkitpy.common.system import stack_utils
 
 
 def current_thread_id():
     thread_id, _ = sys._current_frames().items()[0]
     return thread_id
 
 
 class StackUtilsTest(unittest.TestCase):
 
@@ skipping 21 matching lines @@
         msgs = []
 
         def logger(msg):
             msgs.append(msg)
 
         try:
             raise ValueError
         except:
             stack_utils.log_traceback(logger, sys.exc_info()[2])
         self.assertTrue(msgs)