fix(dropdown): prevent re-show on arrow key nav with auto-close outside

Author: MdFirozAlam-maker

js/src/dropdown.js

@@ -420,7 +420,9 @@ class Dropdown extends BaseComponent {
 
     if (isUpOrDownEvent) {
       event.stopPropagation()
-      instance.show()
+      if(!instance._isShown()) {
+        instance.show()
+      }
       instance._selectMenuItem(event)
       return
     }