1757923.html (520B)
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>