anchor.diff:    }
   
     void addCredentials(Uri url, String realm, HttpClientCredentials cr) {
  -    _credentials.add(new _Credentials(url, realm, cr));
  +    _credentials.add(new _SiteCredentials(url, realm, cr));
     }
   
     set authenticateProxy(
  
positive.code: 
    _AuthenticationScheme get scheme => _AuthenticationScheme.DIGEST;
  
    String authorization(_Credentials credentials, HttpClientRequest request) {
      String requestUri = request._requestUri();
      MD5 hasher = new MD5();
      hasher.add(request.method.codeUnits);
  
negative.code: 
    _AuthenticationScheme get scheme => credentials.scheme;
  
    void authorize(HttpClientRequest request);
  }
  
  class _SiteCredentials extends _Credentials {
    Uri uri;
  
    _SiteCredentials(this.uri, realm, _HttpClientCredentials creds)
    : super(realm, creds);
  
    bool applies(Uri uri, _AuthenticationScheme scheme) {
      if (scheme != null && credentials.scheme != scheme) return false;
      if (uri.domain != this.uri.domain) return false;
  