webkitpy: Make all regex strings use raw string literals.

third_party/WebKit/Tools/Scripts/webkitpy/common/system/user.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 72 matching lines @@
     def _wait_on_list_response(cls, list_items, can_choose_multiple, raw_input):
         while True:
             if can_choose_multiple:
                 response = cls.prompt(
                     "Enter one or more numbers (comma-separated) or ranges (e.g. 3-7), or \"all\": ", raw_input=raw_input)
                 if not response.strip() or response == "all":
                     return list_items
 
                 try:
                     indices = []
-                    for value in re.split("\s*,\s*", response):
+                    for value in re.split(r"\s*,\s*", response):
                         parts = value.split('-')
                         if len(parts) == 2:
                             indices += range(int(parts[0]) - 1, int(parts[1]))
                         else:
                             indices.append(int(value) - 1)
                 except ValueError:
                     continue
 
                 return [list_items[i] for i in indices]
             else:
@@ skipping 40 matching lines @@
         try:
             webbrowser.get()
             return True
         except webbrowser.Error:
             return False
 
     def open_url(self, url):
         if not self.can_open_url():
             _log.warning("Failed to open %s", url)
         webbrowser.open(url)