What object is CustomElementRegistry associated with

[annevk]

Previously: #2545, #2566. Basic test, fails in Chrome and Safari:

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<iframe></iframe>
<script>
async_test(t => {
  const frameCE = self[0].customElements
  self[0].frameElement.onload = t.step_func_done(() => {
    assert_equals(self[0].customElements, frameCE)
  })
  self[0].location.href = "/common/blank.html"
})
</script>

[domenic]

The spec is very clear on this. I will submit a web platform test and file bugs.

[domenic]

Hmm, this test may be being confused by #490.

[domenic]

We should probably collaborate on a shared set of test helpers for "is tied to Window". So e.g. we have web-platform-tests/wpt#5681 but we should also test the issue discovered in #2579 (removing iframes). We can have a shared test helper that generates 3+ tests and then separate test files that test each property.

[domenic]

Bugs filed:

• https://bugs.webkit.org/show_bug.cgi?id=171567
• https://bugs.chromium.org/p/chromium/issues/detail?id=717715