Remove unnecessary pass statements.

third_party/WebKit/Tools/Scripts/webkitpy/common/system/filesystem.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 219 matching lines @@
 
     def sha1(self, path):
         contents = self.read_binary_file(path)
         return hashlib.sha1(contents).hexdigest()
 
     def relpath(self, path, start='.'):
         return os.path.relpath(path, start)
 
     class _WindowsError(exceptions.OSError):
         """Fake exception for Linux and Mac."""
-        pass
 
     def remove(self, path, osremove=os.remove):
         """On Windows, if a process was recently killed and it held on to a
         file, the OS will hold on to the file for a short while.  This makes
         attempts to delete the file fail.  To work around that, this method
         will retry for a few seconds until Windows is done with the file."""
         try:
             exceptions.WindowsError
         except AttributeError:
             exceptions.WindowsError = FileSystem._WindowsError
@@ skipping 20 matching lines @@
     def split(self, path):
         """Return (dirname, basename + '.' + ext)"""
         return os.path.split(path)
 
     def splitext(self, path):
         """Return (dirname + os.sep + basename, '.' + ext)"""
         return os.path.splitext(path)
 
     def make_executable(self, file_path):
         os.chmod(file_path, stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR | stat.S_IRGRP | stat.S_IXGRP)