anchor.diff:    }
   
     void _writeHeader() {
  -    writeSP() => add([_CharCode.SP]);
  -    writeCRLF() => add([_CharCode.CR, _CharCode.LF]);
  -
  -    addString(method);
  +    writeSP() => _ioSink.add([_CharCode.SP]);
  +    writeCRLF() => _ioSink.add([_CharCode.CR, _CharCode.LF]);
  +
  +    _ioSink.addString(method);
       writeSP();
       // Send the path for direct connections and the whole URL for
       // proxy connections.
  
positive.code:     headers._finalize();
  
      // Write headers.
      headers._write(this);
      writeCRLF();
    }
  }
  
negative.code:     headers._finalize();
  
      // Write headers.
      headers._write(_ioSink);
      writeCRLF();
    }
  
  