anchor.diff:      if (uri.startsWith(FILE_PREFIX)) {
         return resolveSymbolicLinks(p.fromUri(Uri.parse(uri)));
       }
  -    if (uri.startsWith(HTTP_PREFIX)) {
  -      return uri;
  -    }
       // We cannot deal with anything else.
       failed.add(uri);
       return null;
  
positive.code: 
    /// Loads an imported resource and returns a [Future] with a [List] of lines.
    /// Returns [null] if the resource could not be loaded.
    Future<List<String>> load(String uri) {
      if (uri.startsWith('http')) {
        Completer c = new Completer();
        HttpClient client = new HttpClient();
        client
            .getUrl(Uri.parse(uri))
            .then((request) => request.close())
            .then((response) => response.transform(UTF8.decoder).toList())
            .then((data) => c.complete(data))
            .then((_) => client.close())
            .catchError((e) {
          failed.add(uri);
          c.complete(null);
        });
        return c.future;
      }
      return new File(uri).readAsLines().catchError((e) => new Future.value());
    }
  }
  
negative.code:   static const DART_PREFIX = 'dart:';
    static const PACKAGE_PREFIX = 'package:';
    static const FILE_PREFIX = 'file://';
  
    @Deprecated('See packageRoot. Removal in 0.7.0.')
    String get pkgRoot => packageRoot;
  