revert: "fix($theme-default): close dropdown on mouseout (fix #2227)"

Author: billyyyyy3320

packages/@vuepress/theme-default/components/DropdownLink.vue

@@ -124,7 +124,6 @@ export default {
     border none
     font-weight 500
     color $textColor
-    pointer-events none
     &:hover
       border-color transparent
     .arrow