fix: check for visibility changes for damage

[kokoISnoTarget]

This fixes #335, by adding restyle damage on visibility changes.

[nicoburns]

Hmm... I feel like visibility should generate "paint" damage rather than "layout" damage (but if this fixes this issue then I'd be inclined to accept the PR anyway for the time being).

[kokoISnoTarget]

Let me quickly check if paint damage would do the trick.

[kokoISnoTarget]

It seems like it at least needs CONSTRUCT_BOX as RestyleDamage for this to work.

[nicoburns]

I'll just merge this for now. Relayouting when visibility changes is probably fine most of the time. And it's better to be a little slow than incorrect. We can figure out why it's not working without and tighten up the damage later.

[nicoburns]

Paint damage should be set automatically by Stylo. Looks like visibility doesn't have damage set (but that means it should default to "full damage" (rebuild_box)) https://github.com/servo/stylo/blob/main/style/properties/longhands/inherited_box.mako.rs#L8

[nicoburns]

Hmm... this still isn't quite right. Without incremental mode the box animates in and out, and the text is a clear bright white. With incremental mode + this PR there's no animation and the text is very faint.