refactor: remove unnecessary Element check

[DOMPurify v3.2.2][1] narrowed down the types of these hooks so that
these are known to have the `Element` type, which means checking the
type of these at runtime is unnecessary.

[1]: https://github.com/cure53/DOMPurify/releases/tag/3.2.2

See: fe3cffb
See: cure53/DOMPurify@4cdfd1f
Cherry-picked-from: 7a1530d

Author: aloisklink

packages/mermaid/src/diagrams/common/common.ts

@@ -33,13 +33,13 @@ function setupDompurifyHooks() {
   const TEMPORARY_ATTRIBUTE = 'data-temp-href-target';
 
   DOMPurify.addHook('beforeSanitizeAttributes', (node) => {
-    if (node instanceof Element && node.tagName === 'A' && node.hasAttribute('target')) {
+    if (node.tagName === 'A' && node.hasAttribute('target')) {
       node.setAttribute(TEMPORARY_ATTRIBUTE, node.getAttribute('target') ?? '');
     }
   });
 
   DOMPurify.addHook('afterSanitizeAttributes', (node) => {
-    if (node instanceof Element && node.tagName === 'A' && node.hasAttribute(TEMPORARY_ATTRIBUTE)) {
+    if (node.tagName === 'A' && node.hasAttribute(TEMPORARY_ATTRIBUTE)) {
       node.setAttribute('target', node.getAttribute(TEMPORARY_ATTRIBUTE) ?? '');
       node.removeAttribute(TEMPORARY_ATTRIBUTE);
       if (node.getAttribute('target') === '_blank') {