Block Bindings: Polish rich-text attribute replacement code.

In the Block Bindings code introduced to replace rich-text attributes, address feedback to:

- reuse an existing bookmark (instead of releasing it), and to
- verify that the expected matching tag closer was found.

Follow-up to [60684].
Props bernhard-reiter, dmsnell.
See #63840.

git-svn-id: https://develop.svn.wordpress.org/trunk@60983 602fd350-edb4-49c9-b593-d223f7449a82

Author: ockham

src/wp-includes/class-wp-block.php

@@ -444,22 +444,25 @@ public function replace_rich_text( $rich_text ) {
 					return false;
 				}
 
-				$depth = $this->get_current_depth();
+				$depth    = $this->get_current_depth();
+				$tag_name = $this->get_tag();
 
-				$this->set_bookmark( '_wp_block_bindings_tag_opener' );
+				$this->set_bookmark( '_wp_block_bindings' );
 				// The bookmark names are prefixed with `_` so the key below has an extra `_`.
-				$tag_opener = $this->bookmarks['__wp_block_bindings_tag_opener'];
+				$tag_opener = $this->bookmarks['__wp_block_bindings'];
 				$start      = $tag_opener->start + $tag_opener->length;
-				$this->release_bookmark( '_wp_block_bindings_tag_opener' );
 
 				// Find matching tag closer.
 				while ( $this->next_token() && $this->get_current_depth() >= $depth ) {
 				}
 
-				$this->set_bookmark( '_wp_block_bindings_tag_closer' );
-				$tag_closer = $this->bookmarks['__wp_block_bindings_tag_closer'];
+				if ( ! $this->is_tag_closer() || $tag_name !== $this->get_tag() ) {
+					return false;
+				}
+
+				$this->set_bookmark( '_wp_block_bindings' );
+				$tag_closer = $this->bookmarks['__wp_block_bindings'];
 				$end        = $tag_closer->start;
-				$this->release_bookmark( '_wp_block_bindings_tag_closer' );
 
 				$this->lexical_updates[] = new WP_HTML_Text_Replacement(
 					$start,