Dropdown: incorrect focus

This applies to use in Chrome.

Testcase https://react.semantic-ui.com/modules/dropdown#dropdown-example-open-on-focus

Steps to Reproduce

1. Click on the down arrow (NOT on the text of the drop-down) of the second dropdown
2. Click on the down arrow again
3. Press 'shift + tab' to navigate to the first dropdown

Expected The first dropdown should now have the focus

Result The second dropdown retains the focus.

** FIX ** This is because when clicking on the down arrow, its the <i ../> element that obtains the focus.

Applying the style pointer-events: none; to the <i .../> element resolves the issue, when the down arrow is clicked focus is passed through to the dropdown component as expected.