This is a testharness.js-based test.
[FAIL] If prototype is not object (null), derives the fallback from NewTarget's GetFunctionRealm (autonomous custom elements)
  assert_equals: Must use the HTMLElement from the realm of NewTarget expected object "[object HTMLElement]" but got object "[object HTMLElement]"
[FAIL] If prototype is not object (undefined), derives the fallback from NewTarget's GetFunctionRealm (autonomous custom elements)
  assert_equals: Must use the HTMLElement from the realm of NewTarget expected object "[object HTMLElement]" but got object "[object HTMLElement]"
[FAIL] If prototype is not object (5), derives the fallback from NewTarget's GetFunctionRealm (autonomous custom elements)
  assert_equals: Must use the HTMLElement from the realm of NewTarget expected object "[object HTMLElement]" but got object "[object HTMLElement]"
[FAIL] If prototype is not object (string), derives the fallback from NewTarget's GetFunctionRealm (autonomous custom elements)
  assert_equals: Must use the HTMLElement from the realm of NewTarget expected object "[object HTMLElement]" but got object "[object HTMLElement]"
Harness: the test ran to completion.