[Dropdown] Placeholder text does not show when allowAdditions is true

[GammaGames]

Bug Report

Steps to reproduce

1. Create a dropdown with js, setting allowAdditions to true
2. Placehodler text does not show up

Expected result

Actual result

Testcase

https://jsfiddle.net/mkov7swt/

Version

2.9.3

[GammaGames]

Workaround is to set the setting after initialization:

$("#first_dropdown").dropdown({
  placeholder: `This text should show up`,
  values: []
}).dropdown("setting", "allowAdditions", true);

https://jsfiddle.net/ztLwuanr/

[lubber-de]

Fixed by #3128
See your adjusted jsfiddle here https://jsfiddle.net/lubber/ws65erf2/12/