Dialog: remove DOM node after destroyed when appendToBody (#9005)

* Form: fix async validate bug

* Form: fix async validate bug

* When dialo's <appendToBody> is true, remove DOM node after destory

packages/dialog/src/component.vue

@@ -177,6 +177,13 @@
           document.body.appendChild(this.$el);
         }
       }
+    },
+
+    destroyed() {
+      // if appendToBody is true, remove DOM node after destroy
+      if (this.appendToBody && this.$el) {
+        this.$el.parentNode.removeChild(this.$el);
+      }
     }
   };
 </script>