Fix implementation detail, move by one not two dashes

Author: dmsnell

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

@@ -1072,7 +1072,7 @@ private function parse_next_tag() {
 							continue 2;
 						}
 
-						$closer_at = $closer_at + 2;
+						$closer_at = $closer_at + 1;
 					}
 				}
 

tests/phpunit/tests/html-api/wpHtmlTagProcessor.php

@@ -1846,6 +1846,7 @@ public function data_abruptly_closed_empty_comments() {
 			'Empty comment with four dashes'     => array( '<hr><!----><hr id=after>' ),
 			'Empty comment with four dashes, improperly closed' => array( '<hr><!----!><hr id=after>--><hr id=final>' ),
 			'Comment with four dashes, improperly closed twice' => array( '<hr><!----!><hr id=after>--!><hr id=final>' ),
+			'Comment with almost-closer inside'  => array( '<hr><!-- ---!><hr id=after>--!><hr id=final>' ),
 		);
 	}