anchor.diff:        buffer.writeln();
       }
   
  +    _writeOpenTagStart(element);
  +    _lastVisitedTag = element.tag;
  +
  +    if (element.isEmpty) {
  +      // Empty element like <hr/>.
  +      _writeOpenTagEnd(element);
  +      return false;
  +    } else {
  +      _elementStack.add(element);
  +      _writeOpenTagEnd(element);
  +      return true;
  +    }
  +  }
  +
  +  /// Whether to trim left if it is contained in `p` or `li`
  +  bool get _trimLeft => true;
  +
  +  void _writeOpenTagStart(Element element) {
       buffer.write('<${element.tag}');
   
       for (var entry in element.attributes.entries) {
  
positive.code:     var content = text.text;
      if (const {'br', 'p', 'li'}.contains(_lastVisitedTag)) {
        var lines = LineSplitter.split(content);
        content = content.contains('<pre>')
            ? lines.join('\n')
            : lines.map((line) => line.trimLeft()).join('\n');
        if (text.text.endsWith('\n')) {
  
negative.code:     if (generatedId != null) {
        buffer.write(' id="${uniquifyId(generatedId)}"');
      }
    }
  
    void _writeOpenTagEnd(Element element) {
      if (element.isEmpty) {
        buffer.write(' />');
  
        if (element.tag == 'br') {
          buffer.writeln();
        }
      } else {
        buffer.write('>');
      }
    }
  
    void _writeCloseTag(Element element) {
      buffer.write('</${element.tag}>');
    }
  
    @override
  