!17540 解决新框架waterflow示例demo报jscrash的问题

Merge pull request !17540 from 李俊峰/waterflow

zh-cn/application-dev/reference/arkui-ts/ts-container-waterflow.md

@@ -253,7 +253,7 @@ struct WaterflowDemo {
 
   build() {
     Column({ space: 2 }) {
-      WaterFlow({ footer: this.itemFoot, scroller: this.scroller }) {
+      WaterFlow({ footer: this.itemFoot.bind(this), scroller: this.scroller }) {
         LazyForEach(this.datasource, (item: number) => {
           FlowItem() {
             Column() {