Big merge from experimental to bleeding edge.

sdk/lib/_internal/compiler/implementation/util/link_implementation.dart

 // Copyright (c) 2011, 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 util_implementation;
 
 class LinkIterator<T> implements Iterator<T> {
-  Link<T> current;
-  LinkIterator(Link<T> this.current);
-  bool get hasNext => !current.isEmpty;
-  T next() {
-    T result = current.head;
-    current = current.tail;
-    return result;
+  T _current;
+  Link<T> _link;
+
+  LinkIterator(Link<T> this._link);
+
+  T get current => _current;
+
+  bool moveNext() {
+    if (_link.isEmpty) {
+      _current = null;
+      return false;
+    }
+    _current = _link.head;
+    _link = _link.tail;
+    return true;
   }
 }
 
 class LinkEntry<T> extends Link<T> {
   final T head;
   Link<T> tail;
 
   LinkEntry(T this.head, [Link<T> tail])
     : this.tail = ((tail == null) ? new Link<T>() : tail);
 
@@ skipping 88 matching lines @@
     if (head == null) {
       head = entry;
     } else {
       lastLink.tail = entry;
     }
     lastLink = entry;
   }
 
   bool get isEmpty => length == 0;
 }