The shipping address/option changed algorithms should not be synchronously poking internal slots

[bzbarsky]

As far as I can tell these algorithms are invoked by the browser UI while things are running in parallel. That is, they do not seem to run off a task. It's a bit hard to say, because nowhere in the spec does it say how the browser goes about invoking these algorithms.

Anyway, assuming these are running in parallel, they should not be modifying values of attributes on objects, because that breaks run-to-completion. They should be doing the value modification off a task; probably the same one that fires the relevant change event.