HTML API: Pass boolean is_pop to stack event constructor

Replace string-based operation parameter with a boolean is_pop flag
passed directly from the call sites. Eliminates a string comparison
in the constructor for every stack event (~1.5M per benchmark run).

Author: sirreal

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

@@ -459,7 +459,7 @@ function ( WP_HTML_Token $token ): void {
 				$current_token         = $this->state->current_token;
 				$is_virtual            = ! isset( $current_token ) || parent::is_tag_closer();
 				$provenance            = ( ! $is_virtual && $token->node_name === $current_token->node_name ) ? 'real' : 'virtual';
-				$this->element_queue[] = new WP_HTML_Stack_Event( $token, WP_HTML_Stack_Event::PUSH, $provenance );
+				$this->element_queue[] = new WP_HTML_Stack_Event( $token, false, $provenance );
 
 				if ( $token->integration_node_type ) {
 					$this->change_parsing_namespace( 'html' );
@@ -474,7 +474,7 @@ function ( WP_HTML_Token $token ): void {
 				$current_token         = $this->state->current_token;
 				$is_virtual            = ! isset( $current_token ) || ! parent::is_tag_closer();
 				$provenance            = ( ! $is_virtual && $token->node_name === $current_token->node_name ) ? 'real' : 'virtual';
-				$this->element_queue[] = new WP_HTML_Stack_Event( $token, WP_HTML_Stack_Event::POP, $provenance );
+				$this->element_queue[] = new WP_HTML_Stack_Event( $token, true, $provenance );
 
 				$adjusted_current_node = $this->get_adjusted_current_node();
 

src/wp-includes/html-api/class-wp-html-stack-event.php

@@ -83,9 +83,9 @@ class WP_HTML_Stack_Event {
 	 * @param string        $operation  One of self::PUSH or self::POP.
 	 * @param string        $provenance "virtual" or "real".
 	 */
-	public function __construct( WP_HTML_Token $token, string $operation, string $provenance ) {
+	public function __construct( WP_HTML_Token $token, bool $is_pop, string $provenance ) {
 		$this->token      = $token;
 		$this->provenance = $provenance;
-		$this->is_pop     = self::POP === $operation;
+		$this->is_pop     = $is_pop;
 	}
 }