| PASS Element.prototype.createElement must add an unresolved custom element to the upgrade candidates map | |
| PASS HTMLElement constructor must throw an TypeError when the top of the construction stack is marked AlreadyConstructed due to a custom element constructor constructing itself after super() call | |
| PASS HTMLElement constructor must throw an TypeError when the top of the construction stack is marked AlreadyConstructed due to a custom element constructor constructing itself before super() call | |
| PASS Upgrading a custom element must throw an TypeError when the returned element is not SameValue as the upgraded element | |
| PASS Upgrading a custom element whose constructor returns a Text node must throw | |
| PASS Upgrading a custom element whose constructor returns an Element must throw | |