fn layout_block_level_children(
layout_context: &LayoutContext<'_>,
positioning_context: &mut PositioningContext,
child_boxes: &[ArcRefCell<BlockLevelBox>],
containing_block: &ContainingBlock<'_>,
sequential_layout_state: Option<&mut SequentialLayoutState>,
collapsible_with_parent_start_margin: CollapsibleWithParentStartMargin,
ignore_block_margins_for_stretch: LogicalSides1D<bool>,
) -> CacheableLayoutResult