Make listDir and createSymlink synchronous in pub.

utils/pub/command_cache.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.
 
 library command_cache;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:json' as json;
 
@@ skipping 15 matching lines @@
       exit(exit_codes.USAGE);
     }
     
     if ((commandOptions.rest[0] != 'list')) {
       log.error('Unknown cache command "${commandOptions.rest[0]}".');
       this.printUsage();
       exit(exit_codes.USAGE);
     }
     
     // TODO(keertip): Add flag to list packages from non default sources
-    return cache.sources.defaultSource.getCachedPackages().then((packages){
-      var packagesObj = <String, Map>{};
-      for (var package in packages){
-        packagesObj[package.name] = {
-          'version': package.version.toString(),
-          'location': package.dir
-        };
-      }
-      // TODO(keertip): Add support for non-JSON format 
-      // and check for --format flag
-      log.message( json.stringify({'packages': packagesObj}));
-    });
+    var packagesObj = <String, Map>{};
+    for (var package in cache.sources.defaultSource.getCachedPackages()) {
+      packagesObj[package.name] = {
+        'version': package.version.toString(),
+        'location': package.dir
+      };
+    }
+
+    // TODO(keertip): Add support for non-JSON format
+    // and check for --format flag
+    log.message(json.stringify({'packages': packagesObj}));
   }  
 }