Nobody has implemented the storage mutex. I think we should not pretend this will eventually happen. Instead we should supplement the spec with appropriate and detailed warnings about how cookies and local/session storage are prone to of multi-window corruption. Including some examples would be good.

If there are alternate patterns that we could recommend, that would be even better. But I think the same problem still occurs in e.g. IndexedDB? Or maybe transactions help there.

Tagging in @inexorabletash as a Blink storage person.

Related: #334 for removing the public API navigator.yieldForStorageUpdates().