anchor.diff:    void render(VContext context) {
       if ((flags & (elementFlag | componentFlag | rootFlag)) != 0) {
         final html.Element r = ref;
  -      var c;
  -
  -      if (type != null) {
  -        if (c == null) {
  -          c = r.classes;
  -        }
  -        c.add(type);
  -      }
   
         if (attrs != null) {
           attrs.forEach((k, v) {
  
positive.code:       }
  
        if (!identical(classes, other.classes)) {
          updateClasses(classes, other.classes, r.classes);
        }
  
        if ((flags & componentFlag) != 0) {
  
negative.code:         });
        }
  
        if ((flags & (elementFlag | componentFlag)) != 0) {
          String className = type;
          if (classes != null) {
            final classesString = classes.join(' ');
            className = className == null ? classesString : className + ' ' + classesString;
          }
          if (className != null) {
            data = className;
            r.className = className;
          }
        } else {
          //html.DomTokenList classList;
          html.CssClassSet classList;
  
          if (type != null) {
            //classList = r.classList;
            classList = r.classes;
            classList.add(type);
          }
  
          if (classes != null) {
            if (classList == null) {
              //classList = r.classList;
              classList = r.classes;
            }
            for (var i = 0; i < classes.length; i++) {
              classList.add(classes[i]);
            }
          }
        }
  
        if ((flags & componentFlag) != 0) {
  