Child navigables can lose document-associated apply-history tasks when
a parent page replaces or destroys the child document. Queue child tasks
with no document association so they remain runnable, and share that
choice for both activation and update-only continuations. Keep top-level
work associated with the active document to preserve initial about:blank
Window reuse.
Also abandon a queued child fetch if its parent document is already gone
before reading the parent's relevant settings object. This matches
browser behavior for detached frame navigations and avoids resuming
stale work against a discarded parent.
The Twinings menu to Black Tea to Earl Grey product flow now reaches the
product main content under Ladybird WebDriver. Existing navigation
coverage and the full LibWeb text suite cover the local history cases.