Fix syntax error in compare_build_artifacts.py.

tools/determinism/compare_build_artifacts.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 """Compare the artifacts from two builds."""
 
 import difflib
 import json
 import optparse
@@ skipping 557 matching lines @@
   parser = optparse.OptionParser(usage='%prog [options]')
   parser.add_option(
       '-f', '--first-build-dir', help='The first build directory.')
   parser.add_option(
       '-s', '--second-build-dir', help='The second build directory.')
   parser.add_option('-r', '--recursive', action='store_true', default=False,
                     help='Indicates if the comparison should be recursive.')
   target = {
       'darwin': 'mac', 'linux2': 'linux', 'win32': 'win'
   }.get(sys.platform, sys.platform)
-  parser.add_option('-t', '--target-platform', help='The target platform.'
+  parser.add_option('-t', '--target-platform', help='The target platform.',
                     default=target, choices=('android', 'mac', 'linux', 'win'))
   options, _ = parser.parse_args()
 
   if not options.first_build_dir:
     parser.error('--first-build-dir is required')
   if not options.second_build_dir:
     parser.error('--second-build-dir is required')
   if not options.target_platform:
     parser.error('--target-platform is required')
 
   return compare_build_artifacts(os.path.abspath(options.first_build_dir),
                                  os.path.abspath(options.second_build_dir),
                                  options.target_platform,
                                  options.recursive)
 
 
 if __name__ == '__main__':
   sys.exit(main())