Enable pylint warnings on presubmit checks.

third_party/WebKit/Tools/Scripts/webkitpy/pylintrc

 # Copyright (c) 2012 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 39 matching lines @@
 # List of plugins (as comma separated values of python modules names) to load,
 # usually to register additional checkers.
 load-plugins=
 
 
 [MESSAGES CONTROL]
 
 # Enable the message, report, category or checker with the given id(s). You can
 # either give multiple identifier separated by comma (,) or put this option
 # multiple time.
-#enable=
+enable=
+  print-statement,
 
 # Disable the message, report, category or checker with the given id(s). You
 # can either give multiple identifier separated by comma (,) or put this option
 # multiple time (only on the command line, not in the configuration file where
 # it should appear only once).
 # CHANGED:
 disable=
   invalid-name,
   missing-docstring,
   line-too-long,
@@ skipping 230 matching lines @@
 # Create a graph of internal dependencies in the given file (report RP0402 must
 # not be disabled)
 int-import-graph=
 
 
 [EXCEPTIONS]
 
 # Exceptions that will emit a warning when being caught. Defaults to
 # "Exception"
 overgeneral-exceptions=Exception