Make hasNext a getter instead of a method.

lib/core/sequences.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 indexed sequence of elements of the same type.
  *
  * This is a primitive interface that any finite integer-indexable
  * sequence can implement.
  * It is intended for data structures where access by index is
@@ skipping 177 matching lines @@
   }
 }
 
 /**
  * Iterates over a [Sequence] in growing index order.
  */
 class SequenceIterator<E> implements Iterator<E> {
   Sequence<E> _sequence;
   int _position;
   SequenceIterator(this._sequence) : _position = 0;
-  bool hasNext() => _position < _sequence.length;
+  bool get hasNext => _position < _sequence.length;
   E next() {
-    if (hasNext()) return _sequence[_position++];
+    if (hasNext) return _sequence[_position++];
     throw new NoMoreElementsException();
   }
 }