This replaces before_remove_attr(), after_remove_attr() and after_set_attr().
The virtual method takes the mutated attribute and an AttributeMutation value
to disambiguate between "attribute is changed", "attribute is added" and
"attribute is removed".
In the case of "attribute is changed", the mutation value contains a reference
to the old value of the mutated attribute, which is used to unregister outdated
named elements when the "id" attribute is changed on an element.
This greatly simplifies the handling of attributes, which in many cases don't
have any specific behaviour whether they are removed or changed or added. It
also fixes a few bugs where things were put in before_remove_attr() instead of
after_remove_attr() (e.g. when removing an href attribute from a base element).
A few helper functions in Element were also renamed and made private.
Parse :active pseudo-class selector.
This is #7258 with a spec link added in doc-comment.
The pseudo-class is never matched, but this can still help with stylesheets like `a:hover, a:active { color: something }` where failing to parse one pseudo-class makes the entire selector list invalid.
I filed #7333 about actually making it match.
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I couldn't find the place in the spec where the precise behavior of
`:active` is described, so I don't set it. However, all the machinery to
keep track of its status is in place.
Improves YouTube.
It's not possible to correctly determine during the css cascade whether the container height
is explicitly specified. Additionally, the spec https://drafts.csswg.org/css2/visudet.html#the-height-property
says this should affect the *used* height, rather than the computed height.
This significantly improves the layout in #6643.
Implement Element.client{Top,Left,Width,Height}
This isn't done, but contains a working implementation of at least `clientTop`. Feedback would be much appreciated: it's probably far from ideal.
Implementing `clientLeft` is straight-forward, I think, but `clientWidth` and `clientHeight` require accessing the `border_box` - and I don't know how that works, yet.
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Introduce VirtualMethods::children_changed()
This virtual method mimics the behaviour of mutation observers and make it more viable than the older child_inserted(), which didn't cover removed nodes and was called as many times as there were inserted nodes.
A few other shortcomings where remove_child() was called directly instead of Node::remove() were also fixed while at it.
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Refactor #[jstraceable] to #[derive(JSTraceable)]
fixes#6524. I had to make an additional change not mentioned in the ticket - adding the `#[feature]` to enable deriving custom traits but I assume that's expected at this time.
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