Repository: flutter
Issue: In iOS version 17.2, when moving the input focus in a WebView, an unknown area appears at the top of the screen.
Labels: platform-ios,p: webview,package,e: OS-version specific,has reproducible steps,P2,team-ios,triaged-ios,found in release: 3.16,found in release: 3.18

### Steps to reproduce

In iOS version 17.2, when moving the input focus in a WebView, an unknown area appears at the top of the screen. 
Please refer to the video.

I am aware that setting 'resizeToAvoidBottomInset' of the scaffold to false prevents the UI from being resized by the keyboard, so the issue is not reproducible.
However, I want the bottom button to be positioned above the keyboard when the body size changed.

This issue is not reproducible on Android, and **it occurs only on iOS version 17.2.**

I believe this may be an issue on the Flutter side due to the OS version update. Your thoughts on this matter are appreciated.

I am using Flutter InAppWebView, and the result is the same when using Flutter WebView
flutter_inappwebview: ^5.7.2+3

![Monosnap screencast 2023-12-21 17-01-31](https://github.com/flutter/flutter/assets/45409353/f7da29fa-19f7-4645-9262-abc1b070d9a3)



### Expected results

When moving the keyboard focus, there should be no unknown area appearing at the top of the screen

### Actual results

In iOS version 17.2, when moving the keyboard focus, an unknown area appears at the top of the screen

### Code sample

<details open><summary>Code sample</summary>

**[Dart code]**
```dart
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';

class TestWebView extends StatelessWidget {
  const TestWebView({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: InAppWebView(
          initialFile: "assets/test2.html",
        ),
      ),
    );
  }
}
```

**[Web code]**
```javascript
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, height=device-height, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
    <title>Mobile Keyboard Inputs</title>
    <script type="application/javascript" src="/assets/packages/flutter_inappwebview_web/assets/web/web_support.js" defer></script>
    <style>
    html,body{
        height:100%;
    }
    .container{
        position:relative;
        height:100%;
    }
    .btnBottom{
        position:fixed;
        width:100%;
        bottom:0;
        left:0;
    }
    </style>
</head>
<body>

<h2>Mobile Keyboard Inputs Example</h2>

<div class="container">
<form action="/submit" method="post">
        <label for="input0">Input Box 0:</label>
        <input type="text" id="input0" name="input0" placeholder="Type something..." />

        <br>

        <label for="input1">Input Box 1:</label>
        <input type="text" id="input1" name="input1" placeholder="Type something..." />

        <br>

        <label for="input2">Input Box 2:</label>
        <input type="number" id="input2" name="input2" pattern="\d*" placeholder="number" />

        <br>

        <label for="input3">Input Box 3:</label>
        <input type="number" id="input3" name="input3" pattern="\d*" placeholder="number" />

        <br>

        <button type="submit" class="btnBottom">버튼</button>
</form>
</div>

</body>
</html>
```

</details>


### Screenshots or Video

<details open>
<summary>Screenshots / Video demonstration</summary>

![Monosnap screencast 2023-12-21 17-01-31](https://github.com/flutter/flutter/assets/45409353/f7da29fa-19f7-4645-9262-abc1b070d9a3)

</details>


### Logs

<details open><summary>Logs</summary>

```console
[Paste your logs here]
```

</details>


### Flutter Doctor output

<details open><summary>Doctor output</summary>

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.16.4, on macOS 14.2 23C64 darwin-arm64,
    locale ko-KR)
[✓] Android toolchain - develop for Android devices (Android SDK
    version 33.0.2)
[✓] Xcode - develop for iOS and macOS (Xcode 15.1)
[✓] Android Studio (version 2022.2)
[✓] VS Code (version 1.85.1)
[✓] Connected device (4 available)
[✓] Network resources

• No issues found!
</details>