minor fix

in some instances closeTag function doesn't really update the state of openedTags when a tag is closed or deleted.

Author: sipryan

src/Html/HtmlFormatter.php

@@ -431,8 +431,8 @@ protected function CloseTag($tag)
         }
       } else {
         $this->output .= "</{$tag}>";
-        $this->openedTags[$tag] = false;
       }
+      $this->openedTags[$tag] = false;
     }
   }