Make listDir and createSymlink synchronous in pub.

utils/pub/utils.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.
 
 /// Generic utility functions. Stuff that should possibly be in core.
 library utils;
 
 import 'dart:async';
 import 'dart:crypto';
 import 'dart:isolate';
@@ skipping 127 matching lines @@
   return false;
 }
 
 /// Returns the hex-encoded sha1 hash of [source].
 String sha1(String source) {
   var sha = new SHA1();
   sha.add(source.codeUnits);
   return CryptoUtils.bytesToHex(sha.close());
 }
 
+// TODO(nweiz): Use Future.of instead of this wherever we don't actually need
+// asynchrony.
 /// Invokes the given callback asynchronously. Returns a [Future] that completes
 /// to the result of [callback].
 ///
 /// This is also used to wrap synchronous code that may thrown an exception to
 /// ensure that methods that have both sync and async code only report errors
 /// asynchronously.
 Future defer(callback()) {
   return new Future.immediate(null).then((_) => callback());
 }
 
@@ skipping 202 matching lines @@
         .then((resolved) => new Pair(key, resolved)));
   });
   return Future.wait(pairs).then((resolvedPairs) {
     var map = {};
     for (var pair in resolvedPairs) {
       map[pair.first] = pair.last;
     }
     return map;
   });
 }