Popper-core: Result of getOuterSizes is not consistent

[rafaelverger]

Steps to reproduce the problem

1. Go to https://popper.js.org/
2. Scroll page to section POPPER ON YOUR SIDE!
3. Wait popper elements on the left side toggle
4. When a new popper appears, scroll the page a bit

_the change is more notable when it is the left popper that is visible_

What is the expected behavior?

Popper element stays on the same position

What went wrong?

Popper element reposition itself due to changes in getComputedStyle result

Any other comments?

Check this gif:

[rafaelverger]

I believe that the error is related to the use of root.getComputedStyle method with an invisible element;

[marciovicente]

I got the same error!