I'd prefer to keep mPaused, because that is a watchable class which we can do something like this.

Considering UpdatePlaybackPseudoClasses() will do more just PLAYING and PAUSED states, it's fine to keep mPaused and set ElementState::PAUSED.

Hmm if I don't create a bit here (only declare :playing in non_ts_pseudo_class_list.rs) then I got this error, which seems the state bit is must to have?

error[E0599]: no associated item named `PLAYING` found for struct `dom::ElementState` in the current scope

As the build error, we can't remove the bit even if it's exclusive or not use (eg. :volume-locked in D281101).

As the build error, we can't remove the bit even if it's exclusive or not use (eg. :volume-locked in D281101).

We definitely have pseudo classes without state bits tho, see MozWindowInactive etc

(But also, you could just use the same state bits, it would be fine invalidation-wise)

I'd prefer to keep mPaused, because that is a watchable class which we can do something like this.

Ah, I missed the Watchable stuff, sorry! Seems fine then.

(But also, you could just use the same state bits, it would be fine invalidation-wise)

@emilio for playing, should I use PAUSED bit, or just keep it empty? Thanks!

Perhaps it'd be good to add a patch at the end of this patch stack (or in a followup bug) that sets this pref to @IS_NIGHTLY_BUILD@?

(assuming any missing/known-broken bits are harmless enough for this to still feel safe to enable in Nightly at least)

Yes, that is exact what my plan is. I will file another bug to turn on the pref for Nightly, and then consider to enable it on all channels after fixing the problem for :stalled.

@emilio If I don't add this, I will get the compile error like below. Do I miss something?

0:12.64 W error[E0407]: method `is_html_media_element` is not a member of trait `Element`
0:12.64 W    --> servo/components/style/invalidation/element/element_wrapper.rs:320:5
0:12.64 W     |
0:12.64 W 320 |       fn is_html_media_element(&self) -> bool {
0:12.64 W     |       ^  --------------------- help: there is an associated function with a similar name: `is_html_slot_element`
0:12.64 W     |  _____|
0:12.64 W     | |
0:12.64 W 321 | |         self.element.is_html_media_element()
0:12.64 W 322 | |     }
0:12.64 W     | |_____^ not a member of trait `Element`
0:12.98 W error[E0407]: method `is_html_media_element` is not a member of trait `selectors::Element`
0:12.98 W     --> servo/components/style/gecko/wrapper.rs:2265:5
0:12.98 W      |
0:12.98 W 2265 |       fn is_html_media_element(&self) -> bool {
0:12.98 W      |       ^  --------------------- help: there is an associated function with a similar name: `is_html_slot_element`
0:12.98 W      |  _____|
0:12.98 W      | |
0:12.98 W 2266 | |         self.is_html_element() && (self.local_name().as_ptr() == local_name!("video").as_ptr() || self.local_name().as_ptr() == local_name!("audio").as_ptr())
0:12.98 W 2267 | |     }
0:12.98 W      | |_____^ not a member of trait `selectors::Element`

ah nvm, I know what I did wrong. Will update.

Will be done in D281809.

using assert_false results in an error assert_false: div should not match :playing expected false got null, so I think we should keep using `assert_equals.

Yes, we need to update the pseudo-class synchronously; using the watch manager would be too late.

using assert_false results in an error assert_false: div should not match :playing expected false got null, so I think we should keep using `assert_equals.

That doesn't make sense, you must have kept querySelector. matches() returns a boolean. Please double check?

My bad, you're right. I will have a follow up to fix this.