Next level not showing in Safari if only one option available

Problem/Motivation

The next select with sub-level of taxonomy terms is not possible to use in Safari if only one option in the first level.
Safari versions: all.

Steps to reproduce

1. Add a new vocabulary
2. Add terms to it but only one term on the first level.
3. Add a field that points to that vocabulary and use "Simple hierarchical select: Chosen" widget.
4. Add a new node(using Safari) and try to add a channel from the second level. The second level won't be possible to open because default value in first level is the only existing one.

Proposed resolution

Remaining tasks

User interface changes