Focus while clicking scrollbars

'''Issue Description''': Typically, clicking on scroll bars doesn't cause the currently focused element to lose focus. However, when I click the scrollbar of an element with ''tabindex'' set to '-1', the focus is lost from the currently focused element. I'm unsure if this is the intended behavior or not, but it seems odd to me. I would appreciate it if someone could clarify whether this is a bug or intentional. '''Steps to reproduce''': 1. Focus on the input element. 2. Click on the scrollbar of the `ul` element. You'll notice that the input element loses its focus. However, if you remove the `tabindex` attribute from the `ul` element and then click on the scrollbar, the input element retains its focus. '''Sample code''': <input type='input'/> <ul style='height: 200px; overflow: scroll; width: 200px' tabindex='-1'> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> <li>option</li> </ul>