Make hashCode a getter and not a method.

utils/pub/package.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 package;
 
 import 'io.dart';
 import 'pubspec.dart';
 import 'source.dart';
 import 'source_registry.dart';
@@ skipping 100 matching lines @@
   /**
    * The metadata used by the package's [source] to identify and locate it. It
    * contains whatever [Source]-specific data it needs to be able to install
    * the package. For example, the description of a git sourced package might
    * by the URL "git://github.com/dart/uilib.git".
    */
   final description;
 
   PackageId(this.name, this.source, this.version, this.description);
 
-  int hashCode() => name.hashCode() ^
-                    source.name.hashCode() ^
-                    version.hashCode();
+  int get hashCode => name.hashCode ^
+                      source.name.hashCode ^
+                      version.hashCode;
 
   bool operator ==(other) {
     if (other is! PackageId) return false;
     // TODO(rnystrom): We're assuming here the name/version/source tuple is
     // enough to uniquely identify the package and that we don't need to delve
     // into the description.
     return other.name == name &&
            other.source.name == source.name &&
            other.version == version;
   }
@@ skipping 79 matching lines @@
 
 class PubspecNameMismatchException implements Exception {
   final String expectedName;
   final String actualName;
 
   PubspecNameMismatchException(this.expectedName, this.actualName);
 
   String toString() => 'The name you specified for your dependency, '
     '"$expectedName", doesn\'t match the name "$actualName" in its pubspec.';
 }