Even if you aren't able to inherit from a form element, can't you still `createElement` one and add it inside your custom element? Surely they don't force you to reimplement <input /> from scratch!
Yes, you can compose them; and then implement a proxy that creates all the methods and attributes that given element class is supposed to have and forward them to the real implementation.
Busywork, so Apple can hold their position. How nice. No, it is not "perfectly fine".
