HTML API: Step past closing HTML, BODY tags

The HTML specification does not close HTML or BODY tags (pop them off the stack of open elements) when their tag closers are encountered. The HTML processor correctly handled this behavior, however it incorrectly "paused" by returning true from the step functions. 

Props jonsurrell, dmsnell, gziolo.
Fixes #62583.



git-svn-id: https://develop.svn.wordpress.org/trunk@59500 602fd350-edb4-49c9-b593-d223f7449a82

Author: gziolo

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

@@ -2318,7 +2318,14 @@ private function step_in_body(): bool {
 				 */
 
 				$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_AFTER_BODY;
-				return true;
+				/*
+				 * The BODY element is not removed from the stack of open elements.
+				 * Only internal state has changed, this does not qualify as a "step"
+				 * in terms of advancing through the document to another token.
+				 * Nothing has been pushed or popped.
+				 * Proceed to parse the next item.
+				 */
+				return $this->step();
 
 			/*
 			 * > An end tag whose tag name is "html"
@@ -4391,7 +4398,14 @@ private function step_after_body(): bool {
 				}
 
 				$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_AFTER_AFTER_BODY;
-				return true;
+				/*
+				 * The HTML element is not removed from the stack of open elements.
+				 * Only internal state has changed, this does not qualify as a "step"
+				 * in terms of advancing through the document to another token.
+				 * Nothing has been pushed or popped.
+				 * Proceed to parse the next item.
+				 */
+				return $this->step();
 		}
 
 		/*
@@ -4586,7 +4600,14 @@ private function step_after_frameset(): bool {
 			 */
 			case '-HTML':
 				$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_AFTER_AFTER_FRAMESET;
-				return true;
+				/*
+				 * The HTML element is not removed from the stack of open elements.
+				 * Only internal state has changed, this does not qualify as a "step"
+				 * in terms of advancing through the document to another token.
+				 * Nothing has been pushed or popped.
+				 * Proceed to parse the next item.
+				 */
+				return $this->step();
 
 			/*
 			 * > A start tag whose tag name is "noframes"