Make isEmpty a getter.

lib/html/src/native_DOMImplementation.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.
 
 class _Utils {
   static List convertToList(List list) {
     // FIXME: [possible optimization]: do not copy the array if Dart_IsArray is fine w/ it.
     final length = list.length;
     List result = new List(length);
     result.setRange(0, length, list);
@@ skipping 85 matching lines @@
   bool containsKey(String key) native "DOMStringMap_containsKey_Callback";
   String operator [](String key) native "DOMStringMap_item_Callback";
   void operator []=(String key, String value) native "DOMStringMap_setItem_Callback";
   String putIfAbsent(String key, String ifAbsent()) => Maps.putIfAbsent(this, key, ifAbsent);
   String remove(String key) native "DOMStringMap_remove_Callback";
   void clear() => Maps.clear(this);
   void forEach(void f(String key, String value)) => Maps.forEach(this, f);
   Collection<String> getKeys() native "DOMStringMap_getKeys_Callback";
   Collection<String> getValues() => Maps.getValues(this);
   int get length => Maps.length(this);
-  bool isEmpty() => Maps.isEmpty(this);
+  bool get isEmpty => Maps.isEmpty(this);
 }
 
 get _printClosure => (s) {
   try {
     window.console.log(s);
   } catch (_) {
     _Utils.print(s);
   }
 };