Add methods to Collection.

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;
 
 abstract class CssClassSet implements Set<String> {
 
   String toString() {
     return Strings.join(new List.from(readClasses()), ' ');
@@ skipping 49 matching lines @@
       dynamic combine(dynamic previousValue, String element)) {
     return readClasses().reduce(initialValue, combine);
   }
   // interface Collection - END
 
   // interface Set - BEGIN
   bool contains(String value) => readClasses().contains(value);
 
   void add(String value) {
     // TODO - figure out if we need to do any validation here
-    // or if the browser natively does enough
+    // or if the browser natively does enough.
     _modify((s) => s.add(value));
   }
 
-  bool remove(String value) {
+  bool remove(Object value) {
+    if (value is! String) return false;
     Set<String> s = readClasses();
     bool result = s.remove(value);
     writeClasses(s);
     return result;
   }
 
   void addAll(Iterable<String> iterable) {
-    // TODO - see comment above about validation
+    // TODO - see comment above about validation.
     _modify((s) => s.addAll(iterable));
   }
 
   void removeAll(Iterable<String> iterable) {
     _modify((s) => s.removeAll(iterable));
   }
 
+  void retainAll(Iterable<String> iterable) {
+    _modify((s) => s.retainAll(iterable));
+  }
+
+  void removeMatching(bool test(String name)) {
+    _modify((s) => s.removeMatching(test));
+  }
+
+  void retainMatching(bool test(String name)) {
+    _modify((s) => s.retainMatching(test));
+  }
+
   bool isSubsetOf(Collection<String> collection) =>
     readClasses().isSubsetOf(collection);
 
   bool containsAll(Collection<String> collection) =>
     readClasses().containsAll(collection);
 
   Set<String> intersection(Collection<String> other) =>
     readClasses().intersection(other);
 
   String get first => readClasses().first;
@@ skipping 46 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);
 }