see pr: niklasvh#2949

Squashed commit of the following:

commit 96cc89a
Author: yuyuyzl <[email protected]>
Date:   Tue Sep 6 10:36:07 2022 +0800

    fix: cleanup iframe first to prevent memory leaks, see niklasvh#1609

commit 485a49e
Author: yuyuyzl <[email protected]>
Date:   Tue Sep 6 10:28:22 2022 +0800

    fix: cleanup iframe first to prevent memory leaks, see niklasvh#1609

Author: nangelina

src/dom/document-cloner.ts

@@ -489,6 +489,16 @@ export class DocumentCloner {
     }
 
     static destroy(container: HTMLIFrameElement): boolean {
+        // cleanup iframe first to prevent memory leaks, see #1609
+        try {
+            const iframe = container.contentWindow;
+            container.src = 'about:blank';
+            if (iframe) {
+                iframe.document.write('');
+                iframe.document.clear();
+                iframe.close();
+            }
+        } catch {}
         if (container.parentNode) {
             container.parentNode.removeChild(container);
             return true;