Optimize HTML Block Type 6 pattern with possessive quantifiers

Author: colinodell

src/Util/RegexHelper.php

@@ -192,7 +192,7 @@ public static function getHtmlBlockOpenRegex(int $type): string
             case HtmlBlock::TYPE_5_CDATA:
                 return '/^<!\[CDATA\[/i';
             case HtmlBlock::TYPE_6_BLOCK_ELEMENT:
-                return '%^<[/]?(?:address|article|aside|base|basefont|blockquote|body|caption|center|col|colgroup|dd|details|dialog|dir|div|dl|dt|fieldset|figcaption|figure|footer|form|frame|frameset|h[123456]|head|header|hr|html|iframe|legend|li|link|main|menu|menuitem|nav|noframes|ol|optgroup|option|p|param|section|source|summary|table|tbody|td|tfoot|th|thead|title|tr|track|ul)(?:\s|[/]?[>]|$)%i';
+                return '%^</?+(?:address|article|aside|base|basefont|blockquote|body|caption|center|col|colgroup|dd|details|dialog|dir|div|dl|dt|fieldset|figcaption|figure|footer|form|frame|frameset|h[123456]|head|header|hr|html|iframe|legend|li|link|main|menu|menuitem|nav|noframes|ol|optgroup|option|p|param|section|source|summary|table|tbody|td|tfoot|th|thead|title|tr|track|ul)(?:\s++|[/]?+[>]|$)%i';
             case HtmlBlock::TYPE_7_MISC_ELEMENT:
                 return '/^(?:' . self::PARTIAL_OPENTAG . '|' . self::PARTIAL_CLOSETAG . ')\\s*$/i';
             default: