[IndexedDB] setVersion with multiple IDBDatabase objects

What do we want to do if the user calls window.indexedDB.open("myDB", "some
description") twice and stores the result as db1 and db2, calls
db1.setVersion(), and then in the success handler does
db2.createObjectStore?  In other words, is the setVersion transaction tied
to the database instance that setVersion was called on, or is it available
to any instance/object that points to that particular database for that
particular origin in that particular page/worker?

J