anchor.diff:    if (FileSystemEntity.isFileSync(path)) {
       return new File(path).absolute.path;
     } else {
  -    throw 'unable to locate path to chrome (${path})';
  -  }
  -}
  -
  -String _chromePath() {
  +    throw 'unable to locate Dartium (${path})';
  +  }
  +}
  +
  +String _chromeStablePath() {
     if (Platform.isLinux) {
       return '/usr/bin/google-chrome';
     } else if (Platform.isMacOS) {
       return '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome';
     } else {
  -    throw 'unable to locate path to chrome';
  +    // TODO: locate Chrome on Windows
  +    throw 'unable to locate Chrome; ${Platform.operatingSystem} not yet supported';
  +  }
  +}
  +
  +String _chromeDevPath() {
  +  if (Platform.isLinux) {
  +    return '/usr/bin/google-chrome-unstable';
  +  } else {
  +    // TODO:
  +    throw 'unable to locate Chrome dev; ${Platform.operatingSystem} not yet supported';
     }
   }
   
  
positive.code:   print('valid options:');
    print(parser.getUsage().replaceAll('\n\n', '\n'));
    print('');
    print('Generally, you should run this tool with either --dartium or --chrome. Optionally, you');
    print('can specify the browser to run the app in, and the application directory to launch.');
  }
  
  String _dartiumPath() {
  
negative.code:   parser.addFlag('dartium',
        help: 'run in dartium, test the app in app/', negatable: false);
    parser.addFlag('chrome',
        help: 'an alias to --chrome-stable', negatable: false);
    parser.addFlag('chrome-stable',
        help: 'run in chrome stable, test the app in build/deploy-test-out/web/', negatable: false);
    parser.addFlag('chrome-dev',
        help: 'run in chrome dev, test the app in build/deploy-test-out/web/', negatable: false);
  
    parser.addOption('appPath', help: 'the application path to run');
    parser.addOption('browserPath', help: 'the path to chrome');
  