Popper: fix not destroy in keep-alive mode, fixed #1359

src/utils/vue-popper.js

@@ -152,5 +152,10 @@ export default {
     this.popperElm &&
     this.popperElm.parentNode === document.body &&
     document.body.removeChild(this.popperElm);
+  },
+
+  // call destroy in keep-alive mode
+  deactivated() {
+    this.$options.beforeDestroy[0].call(this);
   }
 };