Added boolean to toggle.

tools/dom/src/CssClassSet.dart

 // 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.
 
 part of html;
 
 /** A Set that stores the CSS class names for an element. */
 abstract class CssClassSet implements Set<String> {
 
   /**
    * Adds the class [value] to the element if it is not on it, removes it if it
    * is.
+   *
+   * If [shouldAdd] is true, then we always add that [value] to the element. If
+   * [shouldAdd] is false then we always remove [value] from the element.
    */
-  bool toggle(String value);
+  bool toggle(String value, [bool shouldAdd]);
 
   /**
    * Returns [:true:] if classes cannot be added or removed from this
    * [:CssClassSet:].
    */
   bool get frozen;
 
   /**
    * Determine if this element contains the class [value].
    *
@@ skipping 34 matching lines @@
    * [removeClass](http://api.jquery.com/removeClass/).
    */
   void removeAll(Iterable<String> iterable);
 
   /**
    * Toggles all classes specified in [iterable] on element.
    *
    * Iterate through [iterable]'s items, and add it if it is not on it, or
    * remove it if it is. This is the Dart equivalent of jQuery's
    * [toggleClass](http://api.jquery.com/toggleClass/).
+   * If [shouldAdd] is true, then we always add all the classes in [iterable]
+   * element. If [shouldAdd] is false then we always remove all the classes in
+   * [iterable] from the element.
    */
-  void toggleAll(Iterable<String> iterable);
+  void toggleAll(Iterable<String> iterable, [bool shouldAdd]);
 }
 
 /**
  * A set (union) of the CSS classes that are present in a set of elements.
  * Implemented separately from _ElementCssClassSet for performance.
  */
 class _MultiElementCssClassSet extends CssClassSetImpl {
   final Iterable<Element> _elementIterable;
   Iterable<_ElementCssClassSet> _elementCssClassSetIterable;
 
@@ skipping 25 matching lines @@
    *       className property of this element.
    */
   void modify( f(Set<String> s)) {
     _elementCssClassSetIterable.forEach((e) => e.modify(f));
   }
 
   /**
    * Adds the class [value] to the element if it is not on it, removes it if it
    * is.
    */
-  bool toggle(String value) =>
-      _modifyWithReturnValue((e) => e.toggle(value));
+  bool toggle(String value, [bool shouldAdd]) =>
+      _modifyWithReturnValue((e) => e.toggle(value, shouldAdd));
 
   /**
    * Remove the class [value] from element, and return true on successful
    * removal.
    *
    * This is the Dart equivalent of jQuery's
    * [removeClass](http://api.jquery.com/removeClass/).
    */
   bool remove(Object value) => _modifyWithReturnValue((e) => e.remove(value));
 
@@ skipping 18 matching lines @@
       }
     }
     return s;
   }
 
   void writeClasses(Set<String> s) {
     List list = new List.from(s);
     _element.$dom_className = s.join(' ');
   }
 }