Spec: https://storage.spec.whatwg.org
<rdar://problem/82678873>
AFAICT, the only thing left to do here is https://github.com/WebKit/WebKit/blob/a121340322ef72e3e303af58db1c88cb23bf397d/Source/WebCore/Modules/storage/StorageManager.idl#L36 : // FIXME: add Promise<StorageEstimate> estimate(); That said, we don't appear to have any open bug for that?