Make hashCode a getter and not a method.

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;
@@ skipping 108 matching lines @@
       // Builds always come after no build string.
       if (build == null) return -1;
       if (other.build == null) return 1;
 
       return _compareStrings(build, other.build);
     }
 
     return 0;
   }
 
-  int hashCode() => toString().hashCode();
+  int get hashCode => toString().hashCode;
 
   String toString() {
     var buffer = new StringBuffer();
     buffer.add('$major.$minor.$patch');
     if (preRelease != null) buffer.add('-$preRelease');
     if (build != null) buffer.add('+$build');
     return buffer.toString();
   }
 
   /**
@@ skipping 280 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);
   }
 }