Add secret option "live" which compiles more frequently.

dart/site/try/src/user_option.dart

 // Copyright (c) 2014, 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.
 
 library trydart.userOption;
 
+/// Persistent user-configurable option.
+///
+/// Options included in [options] in settings.dart will automatically be
+/// included in the settings UI unless [isHidden] is true.
+///
+/// The value of an option is persisted in [storage] which is normally the
+/// browser's "localStorage", and [name] is a key in "localStorage".  This
+/// means that hidden options can be controlled by opening the JavaScript
+/// console and evaluate:
+///
+///   localStorage['name'] = value // or
+///   localStorage.name = value
+///
+/// An option can be reset to the default value using:
+///
+///   delete localStorage['name'] // or
+///   delete localStorage.name
 class UserOption {
   final String name;
 
   final bool isHidden;
 
   static var storage;
 
   const UserOption(this.name, {this.isHidden: false});
 
   get value => storage[name];
@@ skipping 17 matching lines @@
 class StringUserOption extends UserOption {
   const StringUserOption(String name, {bool isHidden: false})
       : super(name, isHidden: isHidden);
 
   String get value => super.value == null ? '' : super.value;
 
   void set value(String newValue) {
     super.value = newValue;
   }
 }