webkitpy: Make all regex strings use raw string literals.

third_party/WebKit/Tools/Scripts/webkitpy/style/checker.py

 # Copyright (C) 2009 Google Inc. All rights reserved.
 # Copyright (C) 2010 Chris Jerdonek (chris.jerdonek@gmail.com)
 # Copyright (C) 2010 ProFUSION embedded systems
 #
 # 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.
@@ skipping 383 matching lines @@
 
 class CheckerDispatcher(object):
 
     """Supports determining whether and how to check style, based on path."""
 
     def _file_extension(self, file_path):
         """Return the file extension without the leading dot."""
         return os.path.splitext(file_path)[1].lstrip(".")
 
     def _should_skip_file_path(self, file_path, skip_array_entry):
-        match = re.search("\s*png$", file_path)
+        match = re.search(r"\s*png$", file_path)
         if match:
             return False
         if isinstance(skip_array_entry, str):
             if file_path.find(skip_array_entry) >= 0:
                 return True
         elif skip_array_entry.match(file_path):
             return True
         return False
 
     def should_skip_with_warning(self, file_path):
@@ skipping 318 matching lines @@
         checker = self._dispatcher.dispatch(file_path,
                                             style_error_handler,
                                             min_confidence)
 
         if checker is None:
             raise AssertionError("File should not be checked: '%s'" % file_path)
 
         _log.debug("Using class: " + checker.__class__.__name__)
 
         checker.check(lines)