Make hashCode a getter and not a method.

utils/pub/yaml/yaml_map.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.
 
 /**
  * This class wraps behaves almost identically to the normal Dart Map
  * implementation, with the following differences:
  *
  * * It allows null, NaN, boolean, list, and map keys.
  * * It defines `==` structurally. That is, `yamlMap1 == yamlMap2` if they have
@@ skipping 17 matching lines @@
   remove(key) => _map.remove(_wrapKey(key));
   void clear() => _map.clear();
   void forEach(void f(key, value)) =>
     _map.forEach((k, v) => f(_unwrapKey(k), v));
   Collection getKeys() => _map.getKeys().map(_unwrapKey);
   Collection getValues() => _map.getValues();
   int get length => _map.length;
   bool isEmpty() => _map.isEmpty();
   String toString() => _map.toString();
 
-  int hashCode() => _hashCode(_map);
+  int get hashCode => _hashCode(_map);
 
   bool operator ==(other) {
     if (other is! YamlMap) return false;
     return deepEquals(this, other);
   }
 
   /** Wraps an object for use as a key in the map. */
   _wrapKey(obj) {
     if (obj != null && obj is! bool && obj is! List &&
         (obj is! double || !obj.isNan()) &&
@@ skipping 11 matching lines @@
 
 /**
  * A class for wrapping normally-unhashable objects that are being used as keys
  * in a YamlMap.
  */
 class _WrappedHashKey {
   var value;
 
   _WrappedHashKey(this.value);
 
-  int hashCode() => _hashCode(value);
+  int get hashCode => _hashCode(value);
 
   String toString() => value.toString();
 
   /** This is defined as both values being structurally equal. */
   bool operator ==(other) {
     if (other is! _WrappedHashKey) return false;
     return deepEquals(this.value, other.value);
   }
 }
 
@@ skipping 19 matching lines @@
     }
     if (obj is List) {
       // This is probably a really bad hash function, but presumably we'll get this
       // in the standard library before it actually matters.
       int hash = 0;
       for (var e in obj) {
         hash ^= _hashCode(e, parents);
       }
       return hash;
     }
-    return obj.hashCode();
+    return obj.hashCode;
   } finally {
     parents.removeLast();
   }
 }