Make hasNext a getter instead of a method.

tests/compiler/dart2js/code_motion_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.
 
 #import("compiler_helper.dart");
 
 const String TEST_ONE = r"""
 foo(int a, int b, bool param2) {
   for (int i = 0; i < 1; i++) {
     var x = a + 5;  // '+' is now GVNed.
     if (param2) {
       print(a + b);
     } else {
       print(a + b);
     }
   }
 }
 """;
 
 main() {
   String generated = compile(TEST_ONE, entry: 'foo');
   RegExp regexp = const RegExp('a \\+ b');
   Iterator matches = regexp.allMatches(generated).iterator();
-  Expect.isTrue(matches.hasNext());
+  Expect.isTrue(matches.hasNext);
   matches.next();
-  Expect.isFalse(matches.hasNext());
+  Expect.isFalse(matches.hasNext);
 }