Make hasNext a getter instead of a method.

tests/compiler/dart2js_extra/for_in_test.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.
 
 // Test foreach (aka. for-in) functionality.
 
 testIterator(List expect, Iterable input) {
   int i = 0;
   for (var value in input) {
     Expect.isTrue(i < expect.length);
@@ skipping 17 matching lines @@
   MyIterable(List<T> values) : this.values = values;
   Iterator iterator() {
     return new MyListIterator(values);
   }
 }
 
 class MyListIterator<T> implements Iterator<T> {
   final List<T> values;
   int index;
   MyListIterator(List<T> values) : this.values = values, index = 0;
-  bool hasNext() => index < values.length;
+  bool get hasNext => index < values.length;
   T next() => values[index++];
 }
 
 void main() {
   testIterator([], []);
   testIterator([], new MyIterable([]));
   testIterator([1], [1]);
   testIterator([1], new MyIterable([1]));
   testIterator([1,2,3], [1,2,3]);
   testIterator([1,2,3], new MyIterable([1,2,3]));
@@ skipping 22 matching lines @@
 
   // Using the same variable (showing that the expression is evaluated
   // in the outer scope).
   int result = 0;
   var x = [1,2,3];
   for (var x in x) {
     result += x;
   }
   Expect.equals(6, result);
 }