anchor.diff:      if (package == entrypoint.root.name) directories.add("web");
       return directories;
     }
  -
  -  /// Converts a local file path to an [AssetId].
  -  AssetId pathToAssetId(String package, String packageDir, String filePath) {
  -    var relative = path.relative(filePath, from: packageDir);
  -
  -    // AssetId paths use "/" on all platforms.
  -    relative = path.toUri(relative).path;
  -
  -    return new AssetId(package, relative);
  -  }
   }
  
positive.code:         var subdirectory = path.join(packageDir, name);
          var watcher = new DirectoryWatcher(subdirectory);
          watcher.events.listen((event) {
            var id = pathToAssetId(package, packageDir, event.path);
            if (event.type == ChangeType.REMOVE) {
              _barback.removeSources([id]);
            } else {
  
negative.code:         // Skip directories.
          if (!fileExists(entry)) continue;
  
          var id = new AssetId(package, path.relative(entry, from: packageDir));
          files.add(id);
        }
      }
  
  