Index: trunk/src/wp-includes/html-api/class-wp-html-processor.php
===================================================================
--- trunk/src/wp-includes/html-api/class-wp-html-processor.php	(revision 62542)
+++ trunk/src/wp-includes/html-api/class-wp-html-processor.php	(revision 62563)
@@ -3258,36 +3258,58 @@
 			 * > Any other end tag
 			 */
-
-			/*
-			 * Find the corresponding tag opener in the stack of open elements, if
-			 * it exists before reaching a special element, which provides a kind
-			 * of boundary in the stack. For example, a `</custom-tag>` should not
-			 * close anything beyond its containing `P` or `DIV` element.
-			 */
-			foreach ( $this->state->stack_of_open_elements->walk_up() as $node ) {
-				if ( 'html' === $node->namespace && $token_name === $node->node_name ) {
-					break;
-				}
-
-				if ( self::is_special( $node ) ) {
-					// This is a parse error, ignore the token.
-					return $this->step();
-				}
+			return $this->in_body_any_other_end_tag();
+		}
+
+		$this->bail( 'Should not have been able to reach end of IN BODY processing. Check HTML API code.' );
+		// This unnecessary return prevents tools from inaccurately reporting type errors.
+		return false;
+	}
+
+	/**
+	 * Applies the "any other end tag" parsing instructions for the IN BODY insertion mode.
+	 *
+	 * @since 7.1.0
+	 * @ignore
+	 *
+	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
+	 *
+	 * @see https://html.spec.whatwg.org/#parsing-main-inbody
+	 * @see WP_HTML_Processor::step_in_body
+	 *
+	 * @return bool Whether an element was found.
+	 */
+	private function in_body_any_other_end_tag(): bool {
+		$token_name = $this->get_token_name();
+
+		/*
+		 * Find the corresponding tag opener in the stack of open elements, if
+		 * it exists before reaching a special element, which provides a kind
+		 * of boundary in the stack. For example, a `</custom-tag>` should not
+		 * close anything beyond its containing `P` or `DIV` element.
+		 */
+		foreach ( $this->state->stack_of_open_elements->walk_up() as $node ) {
+			if ( 'html' === $node->namespace && $token_name === $node->node_name ) {
+				break;
 			}
 
-			$this->generate_implied_end_tags( $token_name );
-			if ( $node !== $this->state->stack_of_open_elements->current_node() ) {
-				// @todo Record parse error: this error doesn't impact parsing.
+			if ( self::is_special( $node ) ) {
+				// This is a parse error, ignore the token.
+				return $this->step();
 			}
-
-			foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
-				$this->state->stack_of_open_elements->pop();
-				if ( $node === $item ) {
-					return true;
-				}
+		}
+
+		$this->generate_implied_end_tags( $token_name );
+		if ( $node !== $this->state->stack_of_open_elements->current_node() ) {
+			// @todo Record parse error: this error doesn't impact parsing.
+		}
+
+		foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
+			$this->state->stack_of_open_elements->pop();
+			if ( $node === $item ) {
+				return true;
 			}
 		}
 
-		$this->bail( 'Should not have been able to reach end of IN BODY processing. Check HTML API code.' );
+		$this->bail( 'Should not have been able to reach end of "any other end tag" IN BODY processing. Check HTML API code.' );
 		// This unnecessary return prevents tools from inaccurately reporting type errors.
 		return false;