Make hasNext a getter instead of a method.

lib/coreimpl/queue.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.
 
 
 /**
  * An entry in a doubly linked list. It contains a pointer to the next
  * entry, the previous entry, and the boxed element.
  */
 class DoubleLinkedQueueEntry<E> {
@@ skipping 231 matching lines @@
 }
 
 class _DoubleLinkedQueueIterator<E> implements Iterator<E> {
   final _DoubleLinkedQueueEntrySentinel<E> _sentinel;
   DoubleLinkedQueueEntry<E> _currentEntry;
 
   _DoubleLinkedQueueIterator(_DoubleLinkedQueueEntrySentinel this._sentinel) {
     _currentEntry = _sentinel;
   }
 
-  bool hasNext() {
+  bool get hasNext {
     return _currentEntry._next !== _sentinel;
   }
 
   E next() {
-    if (!hasNext()) {
+    if (!hasNext) {
       throw const NoMoreElementsException();
     }
     _currentEntry = _currentEntry._next;
     return _currentEntry.element;
   }
 }