Rim of beaker doesn't disappear behind solid

[ghost]

For phetsims/qa#263. The rim of the beaker overlaps with the iron or brick. It shouldn't be visible. Seen on macOS 10.14 + Chrome.

Just documenting so that it can be fixed when we have some time.

[ghost]

Assigning @ariel-phet for prioritization.

[ariel-phet]

This would be nice to fix, but not a showstopper for 1.0

Marking low priority, but feel free to defer

[chrisklus]

@jbphet and I discussed this and agreed that it wouldn't be fixable unless we restructured the implementation of the model element nodes. Closing.