This removes a set of complex reference cycles between DOM, layout tree
and browsing context.
It also makes lifetimes much easier to reason about, as the DOM and
layout trees are now free to keep each other alive.
This means we can instantiate them for pseudo-elements, which don't have
an associated Element. They all pass it to their parent as a
`Layout::Node*` and handle a lack of `layout_node()` already so this
won't affect any functionality.
Previously, these were added during layout. This didn't fit into the new
world where layout doesn't mutate the tree incrementally, so this patch
adds logic to Layout::TreeBuilder for adding a marker to each list-item
box after its children have been constructed.
This property represents the CSS content size, so let's reduce ambiguity
by using the spec terminology.
We also bring a bunch of related functions along for the ride.
There's a subtle difference here. A "block box" in the spec is a
block-level box, while a "block container" is a box whose children are
either all inline-level boxes in an IFC, or all block-level boxes
participating in a BFC.
Notably, an "inline-block" box is a "block container" but not a "block
box" since it is itself inline-level.
Previously they were positioned with a fixed offset. However this lead
to wider markers with more than one character to collide with the
element itself.
Now the ListItemMarkerBox generates and stores the appropriate String
in its constructor and sets its own width according to that.
The ListItemBox then lays out the Marker taking this width into
account.
This also made the painting a lot easier since we don't generate the
needed Strings every time we repaint, just once.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
The bullet point should not be centered in the height of the list item,
but rather stay in front of the first line.
So, instead of giving the marker the full height of the ListItemBox,
it gets the height of a single line.
This closes#6384
