Refactor Future constructors.

tools/release/version.dart

 // Copyright (c) 2013, 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 functionality for getting dart version numbers using
  * our standard version construction method. Systems that does not include this
  * file should emulate the structure for revision numbers that we have here.
  *
  * The version number of a dart build is constructed as follows:
@@ skipping 131 matching lines @@
         } catch(e) {
           return 0;
         }
       }
     }
     return 0;
   }
 
   Future<int> getRevision() {
     if (repositoryType == RepositoryType.UNKNOWN) {
-      return new Future.immediate(0);
+      return new Future.value(0);
     }
     var isSvn = repositoryType == RepositoryType.SVN;
     var command = isSvn ? "svn" : "git";
     command = "$command${getExecutableSuffix()}";
     var arguments = isSvn ? ["info"] : ["svn", "info"];
     ProcessOptions options = new ProcessOptions();
     // Run the command from the root to get the last changed revision for this
     // "branch". Since we have both trunk and bleeding edge in the same
     // repository and since we always build TOT we need this to get the
     // right version number.
@@ skipping 54 matching lines @@
   static RepositoryType guessType() {
     if (new Directory(".svn").existsSync()) return RepositoryType.SVN;
     if (new Directory(".git").existsSync()) return RepositoryType.GIT;
     return RepositoryType.UNKNOWN;
   }
 
   String toString() => name;
 
   final String name;
 }