fix(dropdown): sizer element is created every time dropdown is initialized

Author: ryamaguchi0220

src/definitions/modules/dropdown.js

@@ -4035,7 +4035,7 @@ $.fn.dropdown.settings = {
     message      : '.message',
     menuIcon     : '.dropdown.icon',
     search       : 'input.search, .menu > .search > input, .menu input.search',
-    sizer        : '> input.sizer',
+    sizer        : '> span.sizer',
     text         : '> .text:not(.icon)',
     unselectable : '.disabled, .filtered',
     clearIcon    : '> .remove.icon'