Remove unused imports in webkitpy with using autoflake.

third_party/WebKit/Tools/Scripts/webkitpy/tool/servers/layouttestsserver.py

 # Copyright (c) 2010 Google Inc. All rights reserved.
 # Copyright (C) 2014 Samsung Electronics. 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
@@ skipping 13 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 time
 import json
 import BaseHTTPServer
 import subprocess
-from subprocess import Popen, PIPE, STDOUT
+from subprocess import STDOUT
 
 from webkitpy.common.webkit_finder import WebKitFinder
 from webkitpy.common.system.filesystem import FileSystem
 from webkitpy.tool.servers.reflectionhandler import ReflectionHandler
 
 
 class LayoutTestsHTTPServer(BaseHTTPServer.HTTPServer):
 
     def __init__(self, httpd_port, config):
         server_name = ""
@@ skipping 25 matching lines @@
             self.wfile.write(html_output)
             self.wfile.flush()
             time.sleep(0.05)
         process.wait()
 
     def do_OPTIONS(self):
         self.send_response(200, "ok")
         self.send_header('Access-Control-Allow-Origin', '*')
         self.send_header('Access-Control-Allow-Methods', 'GET, POST, OPTIONS')
         self.send_header("Access-Control-Allow-Headers", "Content-type")