Commit Martin's patch for pub + lib_v2.

utils/pub/validator/lib.dart

Index: utils/pub/validator/lib.dart
diff --git a/utils/pub/validator/lib.dart b/utils/pub/validator/lib.dart
index 6afeb88fb0e5a0b5556ab4448bd6942cb0a18c47..c9c5aba4a6f8ea53d1bc084e57333dfb909b6f30 100644
--- a/utils/pub/validator/lib.dart
+++ b/utils/pub/validator/lib.dart
@@ -4,6 +4,7 @@
 
 library lib_validator;
 
+import 'dart:async';
 import 'dart:io';
 
 import '../entrypoint.dart';
@@ -22,7 +23,7 @@ class LibValidator extends Validator {
   Future validate() {
     var libDir = join(entrypoint.root.dir, "lib");
 
-    return dirExists(libDir).chain((libDirExists) {
+    return dirExists(libDir).then((libDirExists) {
       if (!libDirExists) {
         errors.add('You must have a "lib" directory.\n'
             "Without that, users cannot import any code from your package.");