Make listDir and createSymlink synchronous in pub.

utils/pub/command_lish.dart

Index: utils/pub/command_lish.dart
diff --git a/utils/pub/command_lish.dart b/utils/pub/command_lish.dart
index c2f25290993394ed67d12f0a83a2c945035c8658..1948ba163a37f80530a02c2955b5eaeaee08a6e8 100644
--- a/utils/pub/command_lish.dart
+++ b/utils/pub/command_lish.dart
@@ -146,11 +146,9 @@ class LishCommand extends PubCommand {
                         "--exclude-standard"]);
       }
 
-      return listDir(rootDir, recursive: true).then((entries) {
-        return entries
-            .where(fileExists) // Skip directories and broken symlinks.
-            .map((entry) => path.relative(entry, from: rootDir));
-      });
+      return listDir(rootDir, recursive: true)
+          .where(fileExists) // Skip directories and broken symlinks.
+          .map((entry) => path.relative(entry, from: rootDir));
     }).then((files) => files.where(_shouldPublish).toList());
   }