Reapply "Make Comparable generic."

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, VersionConstraint {
+class Version implements Comparable<Version>, VersionConstraint {
   /// No released version: i.e. "0.0.0".
   static Version get none => new Version(0, 0, 0);
 
   static final _PARSE_REGEX = new 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 393 matching lines @@
 
 class _EmptyVersion implements VersionConstraint {
   const _EmptyVersion();
 
   bool get isEmpty => true;
   bool get isAny => false;
   bool allows(Version other) => false;
   VersionConstraint intersect(VersionConstraint other) => this;
   String toString() => '<empty>';
 }