Repository: flutter
Issue: TextField selection handles overlap widgets
Labels: a: text input,framework,f: material design,a: layout,has reproducible steps,found in release: 3.3,found in release: 3.4,team-design,triaged-design

![textfield_handle_bug](https://user-images.githubusercontent.com/3614291/84343200-82ab2900-ab75-11ea-9beb-e603293283f1.gif)

```
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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: SafeArea(
        child: Column(
          children: <Widget>[
            Expanded(
              child: SingleChildScrollView(
                child: Column(
                  children: <Widget>[
                    ...List.generate(
                      10,
                      (index) => Container(
                        decoration: BoxDecoration(
                          border: Border.all(),
                        ),
                        margin: const EdgeInsets.all(16),
                        child: Padding(
                          padding: const EdgeInsets.symmetric(horizontal: 16),
                          child: TextField(
                            textAlign: TextAlign.center,
                          ),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            ),
            Container(
              color: Colors.black12,
              padding: const EdgeInsets.all(16),
              width: double.infinity,
              child: MaterialButton(
                color: Colors.orange,
                child: Text(
                  'Continue',
                  style: TextStyle().copyWith(
                    color: Colors.white,
                  ),
                ),
                onPressed: () {},
              ),
            )
          ],
        ),
      ),
    );
  }
}
```
<details>
  <summary>Logs</summary>
<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[✓] Flutter (Channel master, 1.19.0-6.0.pre.57, on Mac OS X 10.15.5 19F101, locale en-US)
    • Flutter version 1.19.0-6.0.pre.57 at /Users/albertlardizabal/dev/flutter/master
    • Framework revision daddc914c7 (4 hours ago), 2020-06-11 01:35:01 +0200
    • Engine revision e8c13aa012
    • Dart version 2.9.0 (build 2.9.0-14.0.dev 5c1376615e)

 
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at /Users/albertlardizabal/Library/Android/sdk
    • Platform android-29, build-tools 28.0.3
    • ANDROID_HOME = /Users/albertlardizabal/Library/Android/sdk
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.5)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.5, Build version 11E608c
    • CocoaPods version 1.9.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.0)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 46.0.2
    • Dart plugin version 193.7361
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
```

</details>