Make isEmpty a getter.

pkg/dartdoc/lib/src/mirrors/util.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.
 
 #library('util');
 
 /**
  * An abstract map implementation. This class can be used as a superclass for
  * implementing maps, requiring only the further implementation of the
  * [:operator []:], [:forEach:] and [:length:] methods to provide a fully
@@ skipping 39 matching lines @@
     forEach((k,_) => keys.add(k));
     return keys;
   }
 
   Collection<V> getValues() {
     var values = <V>[];
     forEach((_,v) => values.add(v));
     return values;
   }
 
-  bool isEmpty() => length == 0;
+  bool get isEmpty => length == 0;
   V putIfAbsent(K key, V ifAbsent()) {
     if (!containsKey(key)) {
       V value = this[key];
       this[key] = ifAbsent();
       return value;
     }
     return null;
   }
 
   V remove(K key) {
@@ skipping 93 matching lines @@
 
   void forEach(void f(K key, Vout value)) {
     _map.forEach((K k, Vin v) {
       var value = _filter(v);
       if (value != null) {
         f(k, value);
       }
     });
   }
 }