dom/base/crashtests/1757923.html

   1 <!DOCTYPE html>
   2 <html>
   3   <head>
   4     <script>
   5       class CustomElement extends HTMLElement {
   6         constructor () {
   7           super();
   8         }
   9       }
  10
  11       let element = document.createElement("custom-element");
  12       customElements.define("custom-element", CustomElement);
  13       customElements.upgrade(element);
  14
  15       const internals = element.attachInternals();
  16       element = undefined;
  17       SpecialPowers.forceGC();
  18       SpecialPowers.forceCC();
  19       internals.shadowRoot;
  20     </script>
  21   </head>
  22 </html>