pub trait LayoutDocumentHelpers<'dom> {
// Required methods
fn is_html_document_for_layout(&self) -> bool;
fn quirks_mode(self) -> QuirksMode;
fn style_shared_lock(self) -> &'dom StyleSharedRwLock;
fn shadow_roots(self) -> Vec<LayoutDom<'dom, ShadowRoot>>;
fn shadow_roots_styles_changed(self) -> bool;
fn flush_shadow_roots_stylesheets(self);
}