wp-includes/html-api/class-wp-html-active-formatting-elements.php:102Inserts a "marker" at the end of the list of active formatting elements.
public function insert_marker(): void { $this->push( new WP_HTML_Token( null, 'marker', false ) ); }Introduced in 6.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/html-api/class-wp-html-active-formatting-elements.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.