Change default dom.py to use ReleaseX64 (matching the default vm/dart2js arch)

tools/dom/dom.py

 #!/usr/bin/python
 
 # Copyright (c) 2013, 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 makes it easy to execute common DOM-related tasks
 
 import os
 import subprocess
@@ skipping 121 matching lines @@
   ]
   if argv:
     cmd.append(argv.pop(0))
   else:
     print(
         'Test commands should be followed by tests to run. Defaulting to html')
     cmd.append('html')
   return call(cmd)
 
 def test_server():
-  start_test_server(5400, os.path.join('out', 'ReleaseIA32'))
+  start_test_server(5400, os.path.join('out', 'ReleaseX64'))
 
 def test_server_dartium():
   start_test_server(5500, os.path.join('..', 'out', 'Release'))
 
 def start_test_server(port, build_directory):
   print('Browse tests at '
       '\033[94mhttp://localhost:%d/root_build/generated_tests/\033[0m' % port)
   return call([
     utils.DartBinary(),
     os.path.join('tools', 'testing', 'dart', 'http_server.dart'),
@@ skipping 52 matching lines @@
       help();
       success = False
       break
     returncode = commands[command][0]()
     success = success and not bool(returncode)
 
   sys.exit(not success)
 
 if __name__ == '__main__':
   main()