Dropdown: take care of disabled triggering element

packages/dropdown/src/dropdown.vue

@@ -77,6 +77,7 @@
           ? this.$refs.trigger.$el
           : this.$slots.default[0].elm;
 
+        if (triggerElm.disabled) return;
         if (trigger === 'hover') {
           triggerElm.addEventListener('mouseenter', show);
           triggerElm.addEventListener('mouseleave', hide);