Repository: flutter
Issue: [Web][TextField] canceling suggest dialog using ESC key, the dialog will close too
Labels: a: text input,platform-web,a: desktop,has reproducible steps,P2,found in release: 2.10,found in release: 2.13,team-text-input,triaged-text-input

This is what happens when I typing in a text field in a dialog.
If I enter in Japanese, the suggestion dialog will be displayed, and often use ESC key to cancel the suggest.
and If I use ESC key, the dialog will be close too.

## Steps to Reproduce

this is the simplest code
```
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';

class SamplePage extends StatefulWidget {

  SamplePage(): super();

  @override
  SamplePageState createState() => SamplePageState();
}

class SamplePageState extends State<SamplePage> with WidgetsBindingObserver {
  @override
  void initState(){
    super.initState();

    SchedulerBinding.instance?.addPostFrameCallback((_){ 
      showDialog( context: context, builder: (BuildContext context) => SampleDialog(), );
    });
  }

  Widget build(BuildContext context){
    Widget bodyScaffold = Scaffold(
      body: Container(
        child: Text("parent"),
        padding : EdgeInsets.all(30),
      ),
    );

    return bodyScaffold;
  }
}


class SampleDialog extends StatefulWidget {
  @override
  _SampleDialogState createState() => _SampleDialogState();
}

class _SampleDialogState extends State<SampleDialog> {

  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      content : Container(
        padding : EdgeInsets.all(30),
        child   : TextField(),
      ),
    );
  }

}

```


1. Run `flutter run -d chrome`.
2. Input text in japanese lang
3. press down arrow key when suggest dialog is shown
4. press ESC

**Expected results:**
only Suggest dialog will be closed

this is sample video
![expect](https://user-images.githubusercontent.com/7422251/115143570-206b6080-a083-11eb-8ae9-5b94c0f63dd0.gif)
(The suggestion dialog is not displayed due to recording reasons )

**Actual results:**
the dialog will be close too 

this is the video
![actual](https://user-images.githubusercontent.com/7422251/115143573-22352400-a083-11eb-9a6a-1ceb7d5dfba0.gif)
(The suggestion dialog is not displayed due to recording reasons )

<details>
  <summary>Logs</summary>

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[√] Flutter (Channel stable, 2.0.4, on Microsoft Windows [Version 10.0.19042.928], locale ja-JP)
    • Flutter version 2.0.4 at C:\src\flutter
    • Framework revision b1395592de (2 weeks ago), 2021-04-01 14:25:01 -0700
    • Engine revision 2dce47073a
    • Dart version 2.12.2

[√] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
    • Android SDK at C:\Users\hatadev\AppData\Local\Android\sdk
    • Platform android-30, build-tools 29.0.2
    • Java binary at: C:\Program Files\Android\Android Studio1\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 Studio1
    • 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 1.55.2)
    • VS Code at C:\Users\hatadev\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.21.0

[√] Connected device (2 available)
    • Chrome (web) • chrome • web-javascript • Google Chrome 90.0.4430.72
    • Edge (web)   • edge   • web-javascript • Microsoft Edge 90.0.818.39
```

</details>