anchor.diff:    }
   
     void authorize(_Credentials credentials, HttpClientRequest request) {
  -    request.headers.set(HttpHeaders.AUTHORIZATION, authorization(credentials, request));
  +    request.headers.set(HttpHeaders.AUTHORIZATION,
  +                        authorization(credentials, request));
     }
   
     void authorizeProxy(_ProxyCredentials credentials,
  
positive.code:   }
  
    void addCredentials(Uri url, String realm, HttpClientCredentials cr) {
      _credentials.add(new _Credentials(url, realm, cr));
    }
  
    set authenticateProxy(
  
negative.code:     credentials.authorize(this, request);
      used = true;
    }
  }
  
  
  class _ProxyCredentials extends _Credentials {
    String host;
    int port;
  
    _ProxyCredentials(this.host,
                      this.port,
                      realm,
                      _HttpClientCredentials creds)
    : super(realm, creds);
  
  
    bool applies(_Proxy proxy, _AuthenticationScheme scheme) {
      return proxy.host == host && proxy.port == port;
    }
  
    void authorize(HttpClientRequest request) {
      // Digest credentials cannot be used without a nonce from the
      // server.
      if (credentials.scheme == _AuthenticationScheme.DIGEST &&
          nonce == null) {
        return;
      }
      credentials.authorizeProxy(this, request);
    }
  }
  
  
  