Make listDir and createSymlink synchronous in pub.

utils/pub/hosted_source.dart

Index: utils/pub/hosted_source.dart
diff --git a/utils/pub/hosted_source.dart b/utils/pub/hosted_source.dart
index 4d6626f594d6f0f26878399b563ad89c48041d2f..59702fb0764a605fb7de414542bad47220b5f69c 100644
--- a/utils/pub/hosted_source.dart
+++ b/utils/pub/hosted_source.dart
@@ -124,10 +124,8 @@ class HostedSource extends Source {
                                _getSourceDirectory(_defaultUrl)); 
       if (!dirExists(cacheDir)) return [];
     
-      return listDir(path.join(cacheDir)).then((entries) {
-        return entries.map((entry) => 
+      return listDir(path.join(cacheDir)).map((entry) => 
           new Package.load(null, entry, systemCache.sources));
-      });  
     });
   }