Make hasNext a getter instead of a method.

lib/html/src/_Collections.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.
 
 /**
  * The [Collections] class implements static methods useful when
  * writing a class that implements [Collection] and the [iterator]
  * method.
  */
 class _Collections {
@@ skipping 36 matching lines @@
   static List filter(Iterable<Object> source,
                      List<Object> destination,
                      bool f(o)) {
     for (final e in source) {
       if (f(e)) destination.add(e);
     }
     return destination;
   }
 
   static bool isEmpty(Iterable<Object> iterable) {
-    return !iterable.iterator().hasNext();
+    return !iterable.iterator().hasNext;
   }
 }