Intermittent TIMEOUT in /performance-timeline/not-restored-reasons/performance-navigation-timing-iframes-without-attributes.tentative.window.html

```
  ▶ TIMEOUT [expected OK] /performance-timeline/not-restored-reasons/performance-navigation-timing-iframes-without-attributes.tentative.window.html
  │   ▶ TIMEOUT [expected FAIL] RemoteContextHelper navigation using BFCache
  └   └   → Test timed out
```