Intermittent FAIL in `/intersection-observer/callback-cross-realm-report-exception.html`

https://github.com/servo/servo/runs/48585375376

```
FAIL [expected PASS] subtest: IntersectionObserver reports the exception from its callback in the callback's global object

assert_array_equals: lengths differ, expected array ["frame1"] length 1, got [] length 0
```