Change option --use_script_snapshot to --use-script-snapshot (easier to type).

tools/create_sdk.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 #
 # A script which will be invoked from gyp to create an SDK.
 #
 # Usage: create_sdk.py sdk_directory
 #
@@ skipping 92 matching lines @@
   if version:
     ReplaceInFiles([os.path.join(sdk_root, 'lib', '_internal', 'compiler',
                                  'implementation', 'compiler.dart')],
                    [(r"BUILD_ID = 'build number could not be determined'",
                      r"BUILD_ID = '%s'" % version)])
   # TODO(dgrove) - add pub once issue 6619 is fixed
   for executable in ['dart2js', 'dartdoc']:
     CopyShellScript(os.path.join(home, 'sdk', 'bin', executable),
                     os.path.join(sdk_root, 'bin'))
 
-  subprocess.call([os.path.join(build_dir, 'gen_snapshot'),
-                   '--script_snapshot=%s' %
+  subprocess.call([os.path.join(build_dir, 'dart'),
+                   '--generate-script-snapshot=%s' %
                    os.path.join(sdk_root, 'lib', '_internal', 'compiler',
                                 'implementation', 'dart2js.dart.snapshot'),
                    os.path.join(sdk_root, 'lib', '_internal', 'compiler',
                                 'implementation', 'dart2js.dart')])
 
 
 
 def Main(argv):
   # Pull in all of the gpyi files which will be munged into the sdk.
   HOME = dirname(dirname(realpath(__file__)))
@@ skipping 184 matching lines @@
     with open(os.path.join(SDK_tmp, 'revision'), 'w') as f:
       f.write(revision + '\n')
       f.close()
 
   Copy(join(HOME, 'README.dart-sdk'), join(SDK_tmp, 'README'))
 
   move(SDK_tmp, SDK)
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv))