$slot function
Assigns a slot in a shadow DOM shadow tree to an element: An element with a slot
attribute is assigned to the slot created by the <slot>
element whose [name](https://developer.mozilla.org/docs/Web/HTML/Element/slot#attr-name)
attribute's value matches that slot
attribute's value.
Implementation
Attribute<GlobalHTMLAttribute> $slot(String value) {
return Attribute('slot', value);
}