HTML API: Use more universal syntax to call Closure variable.

Replace `( $fn )( ...$args )` syntax with equivalent `call_user_func( $fn, ...$args )` to prevent an issue with the WordPress documentation parser. The parser would fail when encountering this syntax, preventing documentation generation.

Developed in WordPress#10907.

Follow-up to [58304].

Props dmsnell, jonsurrell.
See #64224, #61348.


git-svn-id: https://develop.svn.wordpress.org/trunk@61624 602fd350-edb4-49c9-b593-d223f7449a82

Author: sirreal

src/wp-includes/html-api/class-wp-html-open-elements.php

@@ -715,7 +715,7 @@ public function after_element_push( WP_HTML_Token $item ): void {
 		}
 
 		if ( null !== $this->push_handler ) {
-			( $this->push_handler )( $item );
+			call_user_func( $this->push_handler, $item );
 		}
 	}
 
@@ -763,7 +763,7 @@ public function after_element_pop( WP_HTML_Token $item ): void {
 		}
 
 		if ( null !== $this->pop_handler ) {
-			( $this->pop_handler )( $item );
+			call_user_func( $this->pop_handler, $item );
 		}
 	}