Repository: flutter
Issue: TextField is "shifting" when the fontSize is bigger than its constrained height.
Labels: a: text input,framework,f: material design,has reproducible steps,found in release: 3.3,found in release: 3.6,team-design,triaged-design

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## Steps to Reproduce

<!-- You must include full steps to reproduce so that we can reproduce the problem. -->

Hi thanks for Flutter! I encounter a problem as follows: When the constraints (maxHeight) of `TextField` is smaller than the text size (or text line height), TextField will *shift everything up* so *the upper half cannot receive touch events and the lower half cannot be rendered*, which is quite abnormal. See the screenshots for what is happening :)

1. Run `flutter create bug`.
2. Update the files as follows: 

```
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) => MaterialApp(home: MyHomePage());
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text('Bug!')),
        body: Column(children: [
          Container(height: 150, color: Colors.blue),
          ConstrainedBox(
            constraints: BoxConstraints(maxHeight: 100),
            child: TextField(
              style: TextStyle(
                fontSize: 130,
              ),
              controller: TextEditingController(text: 'ABCDEFGHIJKLMN'),
              maxLines: null,
            ),
          ),
          Container(height: 150, color: Colors.green),
        ]));
  }
}
```

Look at screenshot

**Expected results:** <!-- what did you want to see? -->
Should work normally. See the first paragraph of this issue.

**Actual results:**

See these screenshots. Notice that the textfield is "shifting" up!

a. when I open the page
<img src="https://user-images.githubusercontent.com/5236035/98435047-378a4780-210e-11eb-8716-52c3199772d9.png" width ="300"> 

b. when I scroll up the content of textfield a little bit.
<img src="https://user-images.githubusercontent.com/5236035/98435129-3f49ec00-210e-11eb-9e18-4d75eda0f694.png" width ="300">

c. layout inspector shows that, it is the TextField's "InputDecorator" that moves the child (e.g. the text) up!
![image](https://user-images.githubusercontent.com/5236035/98435515-686a7c80-210e-11eb-8414-b31689e6b641.png)
![image](https://user-images.githubusercontent.com/5236035/98435516-73bda800-210e-11eb-88e2-b3887d762a43.png)


<details>
  <summary>Logs</summary>

<!--
      Run your application with `flutter run --verbose` and attach all the
      log output below between the lines with the backticks. If there is an
      exception, please see if the error message includes enough information
      to explain how to solve the issue.
-->

```
N/A
```

<!--
     Run `flutter analyze` and attach any output of that command below.
     If there are any analysis errors, try resolving them before filing this issue.
-->

```
Analyzing bug...                                                        
No issues found! (ran in 1.6s)
```

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[✓] Flutter (Channel stable, 1.22.1, on Mac OS X 10.15.7 19H2, locale
    zh-Hans-CN)
    • Flutter version 1.22.1 at /Users/tom/opt/flutter
    • Framework revision f30b7f4db9 (4 weeks ago), 2020-10-08 10:06:30 -0700
    • Engine revision 75bef9f6c8
    • Dart version 2.10.1
    • Pub download mirror https://pub.flutter-io.cn
    • Flutter download mirror https://storage.flutter-io.cn

 
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at /Users/tom/Library/Android/sdk
    • Platform android-29, build-tools 29.0.3
    • ANDROID_SDK_ROOT = /Users/tom/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_212-release-1586-b4-5784211)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 12.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.1, Build version 12A7403
    • CocoaPods version 1.9.1

[✓] Android Studio (version 3.6)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 48.1.1
    • Dart plugin version 192.8052
    • Java version OpenJDK Runtime Environment (build
      1.8.0_212-release-1586-b4-5784211)

[✓] IntelliJ IDEA Ultimate Edition (version 2020.1)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 46.0.3
    • Dart plugin version 201.7223.43

[!] IntelliJ IDEA Ultimate Edition (version 2020.2.3)
    • IntelliJ at /Users/tom/Applications/JetBrains Toolbox/IntelliJ IDEA
      Ultimate.app
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • For information about installing plugins, see
      https://flutter.dev/intellij-setup/#installing-the-plugins

[!] VS Code (version 1.50.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    ✗ Flutter extension not installed; install from
      https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter

[✓] Proxy Configuration
    • HTTP_PROXY is set
    • NO_PROXY is
      localhost,127.0.0.1,10.96.0.0/12,192.168.99.0/24,192.168.39.0/24,172.17.0.
      0/24,192.168.64.0/24,172.17.0.0/16,192.168.65.0/24,192.168.0.100,192.168.0
      .101,192.168.0.102,192.168.0.103,host.docker.internal
    • NO_PROXY contains 127.0.0.1
    • NO_PROXY contains localhost

[✓] Connected device (1 available)
    • iPhone 12 Pro (mobile) • 7702BE7C-398B-4878-BDF2-50EA7A218386 • ios •
      com.apple.CoreSimulator.SimRuntime.iOS-14-1 (simulator)

! Doctor found issues in 2 categories.
```

</details>