Added boolean to toggle.

sdk/lib/html/html_common/css_class_set.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_common;
 
 abstract class CssClassSetImpl implements CssClassSet {
 
   String toString() {
     return readClasses().join(' ');
   }
 
   /**
    * 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]) {
     Set<String> s = readClasses();
     bool result = false;
-    if (s.contains(value)) {
-      s.remove(value);
-    } else {
+    if (shouldAdd == null) shouldAdd = !s.contains(value);
+    if (shouldAdd) {
       s.add(value);
       result = true;
+    } else {
+      s.remove(value);
     }
     writeClasses(s);
     return result;
   }
 
   /**
    * Returns [:true:] if classes cannot be added or removed from this
    * [:CssClassSet:].
    */
   bool get frozen => false;
@@ skipping 91 matching lines @@
   void removeAll(Iterable<String> iterable) {
     modify((s) => s.removeAll(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) {
-    iterable.forEach(toggle);
+  void toggleAll(Iterable<String> iterable, [bool shouldAdd]) {
+    iterable.forEach((e) => toggle(e, shouldAdd));
   }
 
   void retainAll(Iterable<String> iterable) {
     modify((s) => s.retainAll(iterable));
   }
 
   void removeWhere(bool test(String name)) {
     modify((s) => s.removeWhere(test));
   }
 
@@ skipping 60 matching lines @@
    */
   Set<String> readClasses();
 
   /**
    * Join all the elements of a set into one string and write
    * back to the element.
    * This is intended to be overridden by specific implementations.
    */
   void writeClasses(Set<String> s);
 }