fix(dropdown): set placeholdertext regardless of values

In situations where values are given for a dropdown, but the list is empty (or no value is selected), and also allowAdditions:true is set, a given placeholder wont be shown. That's because internally the dropdownlist does not get cleared when allowAdditions is true which also does not (re-)set the placeholder.

By always trying to show a placeholder this situation gets fixed.

src/definitions/modules/dropdown.js

@@ -126,7 +126,8 @@
                             module.set.initialLoad();
                             module.change.values(settings.values);
                             module.remove.initialLoad();
-                        } else if (module.get.placeholderText() !== '') {
+                        }
+                        if (module.get.placeholderText() !== '') {
                             module.set.placeholderText();
                         }