Repository: flutter
Issue: TextField becomes unresponsive in web browser after using cmd+f (ctrl+f on Windows) to search page
Labels: a: text input,engine,platform-web,has reproducible steps,P2,found in release: 2.3,team-web,triaged-web

## Steps to Reproduce

### Important Factors

- On Flutter web for Mac or Windows, TextField (and TextFormField) work fine until after you use Cmd+f (Ctrl+f on Windows) to find something on the page.
- After closing the find on page box, the TextField becomes unresponsive (can't add, edit, or delete)

To reproduce the issue, run the following application:

<details>
 <summary>Application Code</summary>

`main.dart`

```
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'TextField Issue Simple App',
      home: MyHomePage(title: 'TextField Issue Simple App'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: TextField(
          autofocus: true,
        ),
      ),
    );
  }
}
```

`pubspec.yaml`


```
name: textfield_issue
description: A new Flutter project.

publish_to: 'none'

version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter

  cupertino_icons: ^1.0.2

dev_dependencies:
  flutter_test:
    sdk: flutter

flutter:

  uses-material-design: true
```
</details>

<details>

 <summary>Flutter Doctor Output</summary>

```
[√] Flutter (Channel stable, 2.0.6, on Microsoft Windows [Version 10.0.19042.985], locale en-US)
    • Flutter version 2.0.6 at C:\development\flutter
    • Framework revision 1d9032c7e1 (3 weeks ago), 2021-04-29 17:37:58 -0700
    • Engine revision 05e680e202
    • Dart version 2.12.3

[√] Android toolchain - develop for Android devices (Android SDK version 30.0.2) 
    • Android SDK at C:\development\android-sdk
    • Platform android-30, build-tools 30.0.2
    • ANDROID_SDK_ROOT = C:\development\android-sdk
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java       
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files (x86)\Google\Chrome\Application\chrome.exe

[√] Android Studio (version 4.1.0)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)

[√] VS Code (version 1.56.2)
    • VS Code at C:\Users\josht\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.22.0

[√] Connected device (2 available)
    • Chrome (web) • chrome • web-javascript • Google Chrome 90.0.4430.212
    • Edge (web)   • edge   • web-javascript • Microsoft Edge 90.0.818.62

• No issues found!
```

</details>

### Expected Results
TextField input resumes as normal after closing the find in page box.

### Actual Results
TextField becomes unresponsive after using cmd+f (or ctrl+f on Windows).


https://user-images.githubusercontent.com/80551292/118525114-a9fa6680-b6f3-11eb-821c-f9badc3bd4b4.mp4