fix #1057

Author: krausest

frameworks/keyed/glimmer-2/src/MyTable.ts

@@ -29,7 +29,9 @@ export default class MyTable extends Component {
   }
 
   @action add(): void {
-    this.data = add(this.id, this.data);
+    const result = add(this.id, this.data);
+    this.data = result.data;
+    this.id = result.id;
   }
 
   @action update(): void {

frameworks/keyed/glimmer-2/src/utils/benchmark-helpers.ts

@@ -102,9 +102,9 @@ export const buildData = (id, count = 1000): ItemsSnapshot => {
   return { data, id };
 };
 
-export const add = (id, data): TodoItem[] => {
+export const add = (id, data): ItemsSnapshot => {
   const newData = buildData(id, 1000);
-  return [...data, ...newData.data];
+  return {data: [ ...data, ...newData.data], id: newData.id};
 };
 
 export const run = (id): ItemsSnapshot => {

frameworks/keyed/glimmer/src/ui/components/Glimmer/component.ts

@@ -32,7 +32,9 @@ export default class Glimmer extends Component {
     if (isRendering(this)) {
       return;
     }
-    this.data = add(this.id, this.data).data;
+    const result = add(this.id, this.data);
+    this.data = result.data;
+    this.id = result.id;
   }
 
   public update() {