anchor.diff:  
   import "dart:html";
   import "dart:async";
  +import "dart:convert";
   
   
   
  
positive.code: 
      xhr.setRequestHeader("Accept", "application/x-protobuf");
  
      xhr.onLoad.listen((e) {
        // Note: file:// URIs have status of 0.
        if (xhr.status >= 200 && xhr.status < 300 && !xhr.responseHeaders.containsKey(ERROR_CODE_RESPONSE_HEADER)) {
  
negative.code: 
        } else {
          int errorCode = RemoteServicesErrorCode.RS_COMMUNICATION_ERROR.value;
          String message = UTF8.decode(xhr.response);
  
          if (xhr.responseHeaders.containsKey(ERROR_CODE_RESPONSE_HEADER)) {
            errorCode = xhr.responseHeaders[ERROR_CODE_RESPONSE_HEADER];
          }
  
          _rejectWithError(new ServiceClientException(errorCode, message));
        }
      });
  
      xhr.onError.listen((err) {
        _rejectWithError(new ServiceClientException(RemoteServicesErrorCode.RS_COMMUNICATION_ERROR.value, err.toString()));
      });
  
      xhr.send(requestMessage == null ? null : requestMessage.writeToBuffer());
  