[Bug]: iOS 使用 Flutter_Boost5.0.1 跳转wkwebview 返回后偶现闪屏

### 请描述遇到的问题，以及您所期望的正确的结果

环境如下
在 flutter 3.16.5 ，flutter_boost 5.0.1
跳转原生wkwebview 后，返回出现偶现的闪屏
期望不出现闪屏现象

### 请说明如何操作会遇到上述问题

在 flutter 3.16.5 ，flutter_boost 5.0.1
跳转原生wkwebview 后，返回出现闪屏
点击返回或者策划返回，flutter页面连续闪白屏，

### 在下面填入关键复现代码

```
```

### 复现的平台

iOS

### Flutter SDK版本

3.16.5

### FlutterBoost版本

5.0.1

### 是否延迟初始化FlutterBoost

No

### 解决方案

Reproduce on iOS with Flutter 3.16.5 and flutter_boost 5.0.1 by navigating to a native WKWebView and returning, observing the intermittent white-screen flash. Trace the Flutter page return path and compare successful and failing runs; done means the flash no longer occurs after returning.

Written by the indexing model from the issue text.