This moves LibWeb to using the list of hidden elements from the spec.
Concretely, the following things are now explicitly marked
`display: none` in addition to before:
- elements with the `hidden` attribute
- area
- base
- basefont
- datalist
- param
- rp
The spec also wants `noframes` and `noembed` to be `display: none`,
but since support for frames and embeds doesn't exist yet, these
are omitted for now.
With this, everyone's favorite website http://45.33.8.238/ no longer
displays spans with attribute hidden. (Whitespace handling still
looks a bit off though.)
d670c13a3b