When an element whose descendants include <slot> is being removed, the slottable that being assigned to the slot does not clear its assign_slot. #42182
Description
Describe the bug:
When an element whose descendants include <slot> is being removed, the slottable that being assigned to the slot does not clear its assign_slot.
According to the spec
If node has an inclusive descendant that is a slot:
Run assign slottables for a tree with parent’s root.
Run assign slottables for a tree with node.
Ideally, the slot assignment should be reset, when running the assign slottables for a tree with node algorithm, but we currently fast return
servo/components/script/dom/node.rs
Lines 1546 to 1555 in 22df064
if the node is not a slot element and is not a shadow root with slot element as descendants. But this would affect the below reproducible scenario:
To Reproduce:
Steps to reproduce the behavior.
Consider the below HTML snippet:
<body>
<div id="host">
<div id="content" slot="foo">This is some Text</div>
</div>
<script defer>
let host = document.getElementById("host");
let root = host.attachShadow({mode: "closed"});
let slot = document.createElement("slot");
slot.style = "color: green;"
slot.name = "foo";
let container = document.createElement("div");
container.appendChild(slot);
root.appendChild(container);
container.remove();
// Should be empty, the slot is not in the DOM tree anymore
console.log(slot.assignedNodes());
</script>Click on the toggle button, add log in HTMLSlotElement::assign_slottables() function.
Observe the log: the slot connection would be logged on node insertion. but the slot disconnection would not be triggered on node removal.
Platform:
All platform
cc @xiaochengh