Remove python 2.5 compatibility code.

gcl.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """\
 Wrapper script around Rietveld's upload.py that simplifies working with groups
 of files.
 """
 
+import json
 import optparse
 import os
 import random
 import re
 import string
 import sys
 import tempfile
 import time
 import urllib2
 
 import breakpad  # pylint: disable=W0611
 
-try:
-  import simplejson as json  # pylint: disable=F0401
-except ImportError:
-  try:
-    import json  # pylint: disable=F0401
-  except ImportError:
-    # Import the one included in depot_tools.
-    sys.path.append(os.path.join(os.path.dirname(__file__), 'third_party'))
-    import simplejson as json  # pylint: disable=F0401
 
 import fix_encoding
 import gclient_utils
 import presubmit_support
 import rietveld
 from scm import SVN
 import subprocess2
 from third_party import upload
 
 __version__ = '1.2.1'
@@ skipping 1403 matching lines @@
       raise
     print >> sys.stderr, (
         'AppEngine is misbehaving and returned HTTP %d, again. Keep faith '
         'and retry or visit go/isgaeup.\n%s') % (e.code, str(e))
     return 1
 
 
 if __name__ == "__main__":
   fix_encoding.fix_encoding()
   sys.exit(main(sys.argv[1:]))