Remove unused imports in webkitpy with using autoflake.

third_party/WebKit/Tools/Scripts/webkitpy/common/net/networktransaction_unittest.py

 # Copyright (c) 2010 Google Inc. All rights reserved.
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-import unittest
 
 from urllib2 import HTTPError
 from webkitpy.common.net.networktransaction import NetworkTransaction, NetworkTimeout
 from webkitpy.common.system.logtesting import LoggingTestCase
 
 
 class NetworkTransactionTest(LoggingTestCase):
     exception = Exception("Test exception")
 
     def test_success(self):
@@ skipping 44 matching lines @@
         transaction = NetworkTransaction(initial_backoff_seconds=60 * 60, timeout_seconds=60)
         did_process_exception = False
         did_throw_exception = True
         try:
             transaction.run(lambda: self._raise_500_error())
             did_throw_exception = False
         except NetworkTimeout, e:
             did_process_exception = True
         self.assertTrue(did_throw_exception)
         self.assertTrue(did_process_exception)