Not blocking, and pre-existing, but worth a follow-up: `mock.instances` is still never populated — `fn->instances` is only declared, cleared, lazily created empty, and GC-visited, never written to — so even with the new construct path, `new fn(); fn.mock.instances` is `[]` where Jest gives `[<instance>]`. Since this PR now creates the very `thisObject` that `mock.instances` is meant to record, it'd be a natural place to push it (and, to fully match Jest, push `thisValue` on every call alongside