Support dynamic layout when PhET-iO hides all elements in a container

[zepumph]

From https://github.com/phetsims/phet-io/issues/2003, there are cases that a new phet-io fuzzing feature exposed in this sim, where you could potentially be trying to layout a Node based on another Node with infinite bounds. It has infinite bounds because it has no visible children. Most cases are containers like a Panel with children that are exclusively PhET-iO instrumented elements with an instrumented visibleProperty.

To test the trouble, remove the isFinite() workaround next to the TODO pointing to this issue, run in studio, and hide all the children of the container that is being used in the layout code (right side of the equals sign in the layout code line).

This issue is likely best to be worked on next time this repo is in active development, but up to the responsible dev how to do the layout in this case.