Stop using the Hashable interface.

utils/pub/version.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.
 
 /**
  * Handles version numbers, following the [Semantic Versioning][semver] spec.
  *
  * [semver]: http://semver.org/
  */
 #library('version');
 
 #import('dart:math');
 
 #import('utils.dart');
 
 /** A parsed semantic version number. */
-class Version implements Comparable, Hashable, VersionConstraint {
+class Version implements Comparable, VersionConstraint {
   /** No released version: i.e. "0.0.0". */
   static Version get none => new Version(0, 0, 0);
 
   static const _PARSE_REGEX = const RegExp(
       r'^'                                       // Start at beginning.
       r'(\d+).(\d+).(\d+)'                       // Version number.
       r'(-([0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*))?'   // Pre-release.
       r'(\+([0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*))?'  // Build.
       r'$');                                     // Consume entire string.
 
@@ skipping 392 matching lines @@
         case '<': return new VersionRange(max: version, includeMax: false);
         case '>=': return new VersionRange(min: version, includeMin: true);
         case '>': return new VersionRange(min: version, includeMin: false);
       }
     }
 
     // Otherwise, it must be an explicit version.
     return new Version.parse(text);
   }
 }