anchor.diff:        _inContentBlock = true;
         children = this.children(_ruleChild);
         _inContentBlock = false;
  +    } else {
  +      _expectStatementSeparator();
       }
   
       return new IncludeRule(name, arguments, scanner.spanFrom(start),
  
positive.code:     var urlStart = scanner.state;
      var next = scanner.peekChar();
      if (next == $u || next == $U) {
        return new PlainImportRule(
            new Interpolation([_dynamicUrl()], scanner.spanFrom(urlStart)),
            scanner.spanFrom(start));
      }
  
      var url = string();
      if (_isPlainImportUrl(url)) {
        return new PlainImportRule(
            new Interpolation([scanner.substring(urlStart.position)],
                scanner.spanFrom(urlStart)),
            scanner.spanFrom(start));
      } else if (_inControlDirective || _inMixin) {
        _disallowedAtRule(start);
        return null;
      } else {
        try {
          return new ImportRule(Uri.parse(url), scanner.spanFrom(start));
        } on FormatException catch (error) {
  
negative.code: 
    /// Consumes a statement that's allowed at the top level of the stylesheet.
    Statement _topLevelStatement() {
      if (scanner.peekChar() == $at) {
        return _atRule(_topLevelStatement, root: true);
      } else {
        return _styleRule();
      }
    }
  
    /// Consumes a variable declaration.
  