Fix removed keys in persistent map restoration

[rajanpanth]

Summary

Remove stale persistentMap keys when storage is restored after a page-cache transition.

Problem

The pageshow restore path rebuilds the map data from its initial value and current storage, but previously updated only keys present in that rebuilt object. If a storage key was removed while the page was cached, its old value remained in the in-memory map after restoration.

Changes

• Reuse the map's existing full-object setter during restoration so additions, updates, and removals are reconciled together.
• Add a regression test covering an updated surviving key and a removed stale key.

Testing

• pnpm bnt test/map.test.ts
• pnpm exec bnt --coverage 100 --coverage-exclude "test/*"
• pnpm test:lint
• pnpm test:types
• pnpm test:build
• pnpm test:size

Before

After storage changed from { one: "1", stale: "2" } to { one: "1a" } while the page was cached, restoration produced { one: "1a", stale: "2" }.

After

Restoration replaces the map with the current initial-plus-storage state, producing { one: "1a" } and removing the stale key.

Compatibility

No public API or type changes. The correction affects only persistent-map restoration and reuses existing storage and per-key-listener reconciliation. Runtime behavior is platform-neutral.

Related issue

None; independently reproduced on the current default branch.

[ai]

Thanks. Released in 1.3.5.