Repository: flutter
Issue: Mouse drag in TextField scrolls instead of selecting
Labels: a: text input,framework,a: fidelity,f: scrolling,has reproducible steps,P2,found in release: 2.2,team-framework,triaged-framework

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## Steps to Reproduce

<!-- You must include full steps to reproduce so that we can reproduce the problem. -->
1. Create a web app and add a TextField, make it maxLines to 20.
2. Input texts and click from middle of it.
3. Start to drag from there *Vertically*.
4. The textfield is scrolling instead of selecting the texts from the cursor.


**Expected results:** <!-- what did you want to see? -->
It should act like normal html textfield. 

**Actual results:** <!-- what did you see? -->
The textfield is scrolling instead of selecting texts.

<details>
  <summary>Logs</summary>

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<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[✓] Flutter (Channel stable, 2.2.3, on Mac OS X 10.15.7 19H2 darwin-x64, locale zh-Hans-CN)
    • Flutter version 2.2.3 at /Users/li9s/github/flutter
    • Framework revision f4abaa0735 (4 weeks ago), 2021-07-01 12:46:11 -0700
    • Engine revision 241c87ad80
    • Dart version 2.13.4
    • 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 29.0.2)
    • Android SDK at /Users/li9s/Library/Android/sdk
    • Platform android-30, build-tools 29.0.2
    • ANDROID_HOME = /Users/li9s/Library/Android/sdk
    • ANDROID_SDK_ROOT = /Users/li9s/Library/Android/sdk
    • Java binary at: /Applications/Dev/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Dev/Android Studio.app/Contents
    • 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-b3-6915495)

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/Dev/Android Studio.app/Contents
    • 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-b3-6915495)

[✓] Connected device (2 available)
    • macOS (desktop) • macos  • darwin-x64     • Mac OS X 10.15.7 19H2 darwin-x64
    • Chrome (web)    • chrome • web-javascript • Google Chrome 92.0.4515.107

• No issues found!
```

</details>