Make --leg-only option work when there are arguments passed to test.py.

dart/frog/presubmit.py

 #!/usr/bin/env python
 # Copyright (c) 2011, 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.
 
 import optparse
 import os
 import stat
 import subprocess
 import sys
@@ skipping 101 matching lines @@
   if not options.leg_only:
     SelfHost()
 
   RunCommand('../tools/build.py', '--mode=release')
   test_cmd = ['../tools/test.py', '--report', '--timeout=30',
               '--progress=color', '--mode=release', '--checked']
 
   if options.notest: return
 
   if args:
-    test_cmd.append('--component=frogsh,leg')
+    if options.leg_only:
+      test_cmd.append('--component=leg')
+    else:
+      test_cmd.append('--component=frogsh,leg')
     test_cmd.extend(args)
     RunCommand(*test_cmd, verbose=True)
   else:
     if not options.leg_only:
       # Run frog.py on the corelib tests, so we get some frog.py coverage.
       cmd = test_cmd + ['--component=frog', 'corelib']
       RunCommand(*cmd, verbose=True)
 
       # Run frogium client tests. This is a pretty quick test but
       # tends to uncover different issues due to the size/complexity
@@ skipping 13 matching lines @@
     cmd = test_cmd + ['--component=leg',
                       'language', 'corelib', 'leg', 'leg_only']
     RunCommand(*cmd, verbose=True)
 
 if __name__ == '__main__':
   try:
     sys.exit(main())
   except Error as e:
     sys.stderr.write('%s\n' % e)
     sys.exit(1)