Remove stale todo comment

This comment mentions using a generator for breadcrumbs,
but breadcrumbs are no longer calculated on the fly, so
the comment is outdated.

src/wp-includes/html-api/class-wp-html-processor.php

@@ -1141,11 +1141,7 @@ public function step( $node_to_process = self::PROCESS_NEXT_NODE ): bool {
 	 * Breadcrumbs start at the outermost parent and descend toward the matched element.
 	 * They always include the entire path from the root HTML node to the matched element.
 	 *
-	 * @todo It could be more efficient to expose a generator-based version of this function
-	 *       to avoid creating the array copy on tag iteration. If this is done, it would likely
-	 *       be more useful to walk up the stack when yielding instead of starting at the top.
-	 *
-	 * Example
+	 * Example:
 	 *
 	 *     $processor = WP_HTML_Processor::create_fragment( '<p><strong><em><img></em></strong></p>' );
 	 *     $processor->next_tag( 'IMG' );