There is interesting section in the mdn article of Promises and that's it incumbent settings object tracking. But the most interesting at the end, there is written:

In the above example, the inner text of the will be updated only if the incumbent settings object is tracked. This is because without tracking the incumbent, we may end up using the wrong environment to send the message.

The problem is that it is not correct example, because iframes loading asynchronously and in some cases in firefox, example won't be work too. So I want to see correct example that prove that the only firefox support this feature.

What will be example of the incumbent settings tracking that proving working conception in firefox and vica versa with others browsers?