Introduce WPTServe for running W3C Blink Layout tests

Tools/Scripts/webkitpy/common/system/executive.py

 # Copyright (c) 2009, Google Inc. All rights reserved.
 # Copyright (c) 2009 Apple 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
@@ skipping 68 matching lines @@
     def command_name(self):
         command_path = self.script_args
         if type(command_path) is list:
             command_path = command_path[0]
         return os.path.basename(command_path)
 
 
 class Executive(object):
     PIPE = subprocess.PIPE
     STDOUT = subprocess.STDOUT
+    DEVNULL = open(os.devnull, 'wb')
 
     def _should_close_fds(self):
         # We need to pass close_fds=True to work around Python bug #2320
         # (otherwise we can hang when we kill DumpRenderTree when we are running
         # multiple threads). See http://bugs.python.org/issue2320 .
         # Note that close_fds isn't supported on Windows, but this bug only
         # shows up on Mac and Linux.
         return sys.platform not in ('win32', 'cygwin')
 
     def _run_command_with_teed_output(self, args, teed_output, **kwargs):
@@ skipping 354 matching lines @@
             pool.close()
             pool.join()
 
 
 def _run_command_thunk(cmd_line_and_cwd):
     # Note that this needs to be a bare module (and hence Picklable) method to work with multiprocessing.Pool.
     (cmd_line, cwd) = cmd_line_and_cwd
     proc = subprocess.Popen(cmd_line, cwd=cwd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     stdout, stderr = proc.communicate()
     return (proc.returncode, stdout, stderr)