Support non-elements more thoroughly

[dominicbarnes]

In particular, I'm thinking about the method that binds events to the field in order to revalidate after further input.

It just uses component/event blindly, but I think it could check that the input is an element before calling bind. Also, I figured it could also check if the input is an instance of EventEmitter and use Emitter#on() instead of bind.

[ianstormtaylor]

+1 that sounds really good