Add type annotations to some dart:html closures

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 c948819c93ad06ee4602e65328139dd38c9d1aab..0b22ef7741942959a398083c4d54b78db2ee40b8 100644
--- a/tools/dom/src/CssClassSet.dart
+++ b/tools/dom/src/CssClassSet.dart
@@ -96,12 +96,13 @@ class _MultiElementCssClassSet extends CssClassSetImpl {
 
   Set<String> readClasses() {
     var s = new LinkedHashSet<String>();
-    _elementCssClassSetIterable.forEach((e) => s.addAll(e.readClasses()));
+    _elementCssClassSetIterable.forEach(
+        (_ElementCssClassSet e) => s.addAll(e.readClasses()));
     return s;
   }
 
   void writeClasses(Set<String> s) {
-    var classes = new List.from(s).join(' ');
+    var classes = s.join(' ');
     for (Element e in _elementIterable) {
       e.className = classes;
     }
@@ -117,7 +118,7 @@ class _MultiElementCssClassSet extends CssClassSetImpl {
    *       className property of this element.
    */
   modify( f(Set<String> s)) {
-    _elementCssClassSetIterable.forEach((e) => e.modify(f));
+    _elementCssClassSetIterable.forEach((_ElementCssClassSet e) => e.modify(f));
   }
 
   /**
@@ -125,7 +126,9 @@ class _MultiElementCssClassSet extends CssClassSetImpl {
    * is.
    */
   bool toggle(String value, [bool shouldAdd]) =>
-      _modifyWithReturnValue((e) => e.toggle(value, shouldAdd));
+      _elementCssClassSetIterable.fold(false,
+          (bool changed, _ElementCssClassSet e) =>
+              e.toggle(value, shouldAdd) || changed);
 
   /**
    * Remove the class [value] from element, and return true on successful
@@ -134,10 +137,8 @@ class _MultiElementCssClassSet extends CssClassSetImpl {
    * This is the Dart equivalent of jQuery's
    * [removeClass](http://api.jquery.com/removeClass/).
    */
-  bool remove(Object value) => _modifyWithReturnValue((e) => e.remove(value));
-
-  bool _modifyWithReturnValue(f) => _elementCssClassSetIterable.fold(
-      false, (prevValue, element) => f(element) || prevValue);
+  bool remove(Object value) => _elementCssClassSetIterable.fold(false,
+      (bool changed, _ElementCssClassSet e) => e.remove(value) || changed);
 }
 
 class _ElementCssClassSet extends CssClassSetImpl {
@@ -160,7 +161,6 @@ class _ElementCssClassSet extends CssClassSetImpl {
   }
 
   void writeClasses(Set<String> s) {
-    List list = new List.from(s);
     _element.className = s.join(' ');
   }
 }