Run format-webkitpy and fix long lines.

third_party/WebKit/Tools/Scripts/webkitpy/common/system/filesystem_mock.py

 # Copyright (C) 2009 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 43 matching lines @@
         self.last_tmpdir = None
         self.current_tmpno = 0
         self.cwd = cwd
         self.dirs = set(dirs or [])
         self.dirs.add(cwd)
         for f in self.files:
             d = self.dirname(f)
             while not d in self.dirs:
                 self.dirs.add(d)
                 d = self.dirname(d)
+
     def clear_written_files(self):
         # This function can be used to track what is written between steps in a test.
         self.written_files = {}
 
     def _raise_not_found(self, path):
         raise IOError(errno.ENOENT, path, os.strerror(errno.ENOENT))
 
     def _split(self, path):
         # This is not quite a full implementation of os.path.split
         # http://docs.python.org/library/os.path.html#os.path.split
@@ skipping 419 matching lines @@
         return self.data.readline(length)
 
     def __iter__(self):
         return self.data.__iter__()
 
     def next(self):
         return self.data.next()
 
     def seek(self, offset, whence=os.SEEK_SET):
         self.data.seek(offset, whence)