Get rid of a lot of () for getters.

lib/core/map.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.
 
 /**
  * A [Map] is an associative container, mapping a key to a value.
  * Null values are supported.
  */
 interface Map<K, V> default HashMapImplementation<K extends Hashable, V> {
   /**
@@ skipping 61 matching lines @@
   Collection<K> getKeys();
 
   /**
    * Returns a collection containing all the values in the map.
    */
   Collection<V> getValues();
 
   /**
    * The number of {key, value} pairs in the map.
    */
-  int get length();
+  int get length;
 
   /**
    * Returns true if there is no {key, value} pair in the map.
    */
   bool isEmpty();
 }
 
 /**
  * Hash map version of the [Map] interface. A [HashMap] does not
  * provide any guarantees on the order of keys and values in [getKeys]
@@ skipping 21 matching lines @@
   /**
    * Creates a map with the default implementation.
    */
   LinkedHashMap();
 
   /**
    * Creates a [LinkedHashMap] that contains all key value pairs of [other].
    */
   LinkedHashMap.from(Map<K, V> other);
 }