Stop using the Hashable interface.

utils/pub/yaml/model.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 file contains the node classes for the internal representations of YAML
 // documents. These nodes are used for both the serialization tree and the
 // representation graph.
 
 /** A tag that indicates the type of a YAML node. */
-class _Tag implements Hashable {
+class _Tag {
   // TODO(nweiz): it would better match the semantics of the spec if there were
   // a singleton instance of this class for each tag.
 
   static const SCALAR_KIND = 0;
   static const SEQUENCE_KIND = 1;
   static const MAPPING_KIND = 2;
 
   static const String YAML_URI_PREFIX = 'tag:yaml.org,2002:';
 
   /** The name of the tag, either a URI or a local tag beginning with "!". */
@@ skipping 22 matching lines @@
       return '!!${name.substring(YAML_URI_PREFIX.length)}';
     } else {
       return '!<$name>';
     }
   }
 
   int hashCode() => name.hashCode();
 }
 
 /** The abstract class for YAML nodes. */
-class _Node implements Hashable {
+class _Node {
   /** Every YAML node has a tag that describes its type. */
   _Tag tag;
 
   /** Any YAML node can have an anchor associated with it. */
   String anchor;
 
   _Node(this.tag, [this.anchor]);
 
   bool operator ==(other) {
     if (other is! _Node) return false;
@@ skipping 165 matching lines @@
   String toString() {
     var strContent = Strings.join(content.getKeys().
         map((k) => '${k}: ${content[k]}'), ', ');
     return '$tag {$strContent}';
   }
 
   int hashCode() => super.hashCode() ^ _hashCode(content);
 
   visit(_Visitor v) => v.visitMapping(this);
 }