HTML API: Prevent infinite loop in foreign content reprocessing step.

An infinite loop was discovered in specific situations within foreign content inside the HTML Processor when a given node inside foreign content must be handled in the rules for the current insertion mode.

This patch resolves the loop by handling those nodes directly instead of reprocessing the node, which previously was redirecting control flow back to where the loop started.

Developed in https://github.com/wordpress/wordpress-develop/7347
Discussed in https://core.trac.wordpress.org/ticket/61656

Follow-up to [58868].

Props jonsurrell.
See #61576.



git-svn-id: https://develop.svn.wordpress.org/trunk@59024 602fd350-edb4-49c9-b593-d223f7449a82

Author: dmsnell

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

@@ -4501,7 +4501,7 @@ private function step_in_foreign_content(): bool {
 
 					$this->state->stack_of_open_elements->pop();
 				}
-				return $this->step( self::REPROCESS_CURRENT_NODE );
+				goto in_foreign_content_process_in_current_insertion_mode;
 		}
 
 		/*
@@ -4577,6 +4577,7 @@ private function step_in_foreign_content(): bool {
 				goto in_foreign_content_end_tag_loop;
 			}
 
+			in_foreign_content_process_in_current_insertion_mode:
 			switch ( $this->state->insertion_mode ) {
 				case WP_HTML_Processor_State::INSERTION_MODE_INITIAL:
 					return $this->step_initial();