[selectors] :user-invalid or :user-error

The current draft is very confusing.

https://drafts.csswg.org/selectors-4/#user-pseudos


> 12.3.4. The User-interaction Pseudo-class: :user-invalid
> The :user-invalid pseudo-class represents ...
> The :user-error pseudo-class must ...
> :user-error match an :invalid element ...

> EXAMPLE 36
> it won’t match :user-error until ...

What is defined in this section; :user-invalid or :user-error?

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TAMURA, Kent
Software Engineer, Google