CssClassSet upgrade

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.
+   *
+   * If this corresponds to one element, returns `true` if [value] is present
+   * after the operation, and returns `false` if [value] is absent after the
+   * operation.
+   *
+   * If this corresponds to many elements, `null` is always returned.
    */
   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].
    *
    * This is the Dart equivalent of jQuery's
    * [hasClass](http://api.jquery.com/hasClass/).
    */
   bool contains(String value);
 
   /**
    * Add the class [value] to element.
    *
    * This is the Dart equivalent of jQuery's
    * [addClass](http://api.jquery.com/addClass/).
    *
    * If this corresponds to one element. Returns true if [value] was added to
    * the set, otherwise false.
    *
-   * If this corresponds to many elements, null is always returned.
+   * If this corresponds to many elements, `null` is always returned.
    */
   bool add(String value);
 
   /**
    * 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/).
    */
@@ skipping 20 matching lines @@
    *
    * 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, [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;
-
-  _MultiElementCssClassSet(this._elementIterable) {
-    _elementCssClassSetIterable = new List.from(_elementIterable).map(
-        (e) => new _ElementCssClassSet(e));
-  }
-
-  Set<String> readClasses() {
-    var s = new LinkedHashSet<String>();
-    _elementCssClassSetIterable.forEach(
-        (_ElementCssClassSet e) => s.addAll(e.readClasses()));
-    return s;
-  }
-
-  void writeClasses(Set<String> s) {
-    var classes = s.join(' ');
-    for (Element e in _elementIterable) {
-      e.className = classes;
-    }
-  }
-
-  /**
-   * Helper method used to modify the set of css classes on this element.
-   *
-   *   f - callback with:
-   *   s - a Set of all the css class name currently on this element.
-   *
-   *   After f returns, the modified set is written to the
-   *       className property of this element.
-   */
-  modify( f(Set<String> s)) {
-    _elementCssClassSetIterable.forEach((_ElementCssClassSet 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, [bool shouldAdd]) =>
-      _elementCssClassSetIterable.fold(false,
-          (bool changed, _ElementCssClassSet e) =>
-              e.toggle(value, shouldAdd) || changed);
-
-  /**
-   * 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) => _elementCssClassSetIterable.fold(false,
-      (bool changed, _ElementCssClassSet e) => e.remove(value) || changed);
-}
-
-class _ElementCssClassSet extends CssClassSetImpl {
-
-  final Element _element;
-
-  _ElementCssClassSet(this._element);
-
-  Set<String> readClasses() {
-    var s = new LinkedHashSet<String>();
-    var classname = _element.className;
-
-    for (String name in classname.split(' ')) {
-      String trimmed = name.trim();
-      if (!trimmed.isEmpty) {
-        s.add(trimmed);
-      }
-    }
-    return s;
-  }
-
-  void writeClasses(Set<String> s) {
-    _element.className = s.join(' ');
-  }
-}