Added new version of reduce.

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 readClasses().join(' ');
@@ skipping 40 matching lines @@
   Iterable expand(Iterable f(String element)) => readClasses().expand(f);
 
   bool every(bool f(String element)) => readClasses().every(f);
 
   bool any(bool f(String element)) => readClasses().any(f);
 
   bool get isEmpty => readClasses().isEmpty;
 
   int get length => readClasses().length;
 
-  dynamic reduce(dynamic initialValue,
-      dynamic combine(dynamic previousValue, String element)) {
-    return readClasses().reduce(initialValue, combine);
+  String reduce(String combine(String value, String element)) {
+    return readClasses().reduce(combine);
   }
 
   dynamic fold(dynamic initialValue,
       dynamic combine(dynamic previousValue, String element)) {
     return readClasses().fold(initialValue, combine);
   }
   // interface Collection - END
 
   // interface Set - BEGIN
   /**
@@ skipping 89 matching lines @@
 
   Set<String> difference(Set<String> other) =>
     readClasses().difference(other);
 
   String get first => readClasses().first;
   String get last => readClasses().last;
   String get single => readClasses().single;
   List<String> toList({ bool growable: true }) =>
       readClasses().toList(growable: growable);
   Set<String> toSet() => readClasses().toSet();
-  String min([int compare(String a, String b)]) =>
-      readClasses().min(compare);
-  String max([int compare(String a, String b)]) =>
-      readClasses().max(compare);
   Iterable<String> take(int n) => readClasses().take(n);
   Iterable<String> takeWhile(bool test(String value)) =>
       readClasses().takeWhile(test);
   Iterable<String> skip(int n) => readClasses().skip(n);
   Iterable<String> skipWhile(bool test(String value)) =>
       readClasses().skipWhile(test);
   String firstWhere(bool test(String value), { String orElse() }) =>
       readClasses().firstWhere(test, orElse: orElse);
   String lastWhere(bool test(String value), {String orElse()}) =>
       readClasses().lastWhere(test, orElse: orElse);
@@ skipping 28 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);
 }