Added new version of reduce.

tools/dom/src/CssClassSet.dart

Index: tools/dom/src/CssClassSet.dart
diff --git a/tools/dom/src/CssClassSet.dart b/tools/dom/src/CssClassSet.dart
index 30c0f26066a79e27e33934012f7dba9961da33ee..08d99f848dfef44c386bf9231150dbd5fddfbd15 100644
--- a/tools/dom/src/CssClassSet.dart
+++ b/tools/dom/src/CssClassSet.dart
@@ -58,9 +58,8 @@ abstract class CssClassSet implements Set<String> {
 
   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,
@@ -170,10 +169,6 @@ abstract class CssClassSet implements Set<String> {
   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);