Function layout_2020::flexbox::layout::allocate_free_cross_space_for_flex_line

fn allocate_free_cross_space_for_flex_line(
    resolved_align_content: AlignFlags,
    remaining_free_cross_space: Au,
    remaining_line_count: i32,
) -> (Au, Au)

Align all flex lines per align-content according to https://drafts.csswg.org/css-flexbox/#algo-line-align. Returns the space to add to each line or the space to add after each line.