anchor.diff:    List<TextMarker> getAllMarks() {
       var result = call('getAllMarks');
       if (result is! List) return [];
  -    return new List<TextMarker>.from(
  -        result.map((mark) => new TextMarker(mark)).toList());
  +    return new List.from(result.map((mark) => new TextMarker(mark)));
     }
   
     /**
  
positive.code:   List<TextMarker> findMarksAt(Position pos) {
      var result = callArg('findMarksAt', pos.toProxy());
      if (result is! List) return [];
      return new List<TextMarker>.from(
          result.map((mark) => new TextMarker(mark)).toList());
    }
  
    /**
  
negative.code:   List<TextMarker> findMarks(Position from, Position to) {
      var result = callArgs('findMarks', [from.toProxy(), to.toProxy()]);
      if (result is! List) return [];
      return new List.from(result.map((mark) => new TextMarker(mark)));
    }
  
    /**
  