Fix locale.get_supported_locales(): remove cls parameter

tornado/locale.py

@@ -180,7 +180,7 @@ def load_gettext_translations(directory, domain):
     logging.info("Supported locales: %s", sorted(_supported_locales))
 
 
-def get_supported_locales(cls):
+def get_supported_locales():
     """Returns a list of all the supported locale codes."""
     return _supported_locales