Repository: flutter
Issue: ReorderableListView should add grab handles like on web.
Labels: c: new feature,framework,f: material design,c: proposal,has reproducible steps,found in release: 1.22,found in release: 2.1,team-design,triaged-design

## Steps to Reproduce
 I use VS code and run the application in debug mode (pressing F5). 

1. Run `flutter create --sample=material.ReorderableListView.1 mysample`
2. Run the application on phone (emulator or device)

**Expected results:** <!-- what did you want to see? -->
The same behavior as shown in the docs: https://api.flutter.dev/flutter/material/ReorderableListView-class.html

**Actual results:** <!-- what did you see? -->

1. There are no handles to drag and drop 
2. It is not possible to drag and drop the items

![Screen](https://user-images.githubusercontent.com/48355480/110639901-89bca180-81b0-11eb-947f-90013d877751.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.
-->

```
[  +60 ms] executing: [C:\SDK\flutter/] git -c log.showSignature=false log -n 1 --pretty=format:%H
[  +48 ms] Exit code 0 from: git -c log.showSignature=false log -n 1 --pretty=format:%H
[        ] c5a4b4029c0798f37c4a39b479d7cb75daa7b05c
[        ] executing: [C:\SDK\flutter/] git tag --points-at c5a4b4029c0798f37c4a39b479d7cb75daa7b05c
[  +33 ms] Exit code 0 from: git tag --points-at c5a4b4029c0798f37c4a39b479d7cb75daa7b05c
[        ] 2.0.1
[  +32 ms] executing: [C:\SDK\flutter/] git rev-parse --abbrev-ref --symbolic @{u}
[  +24 ms] Exit code 0 from: git rev-parse --abbrev-ref --symbolic @{u}
[        ] origin/stable
[        ] executing: [C:\SDK\flutter/] git ls-remote --get-url origin 
[  +21 ms] Exit code 0 from: git ls-remote --get-url origin
[        ] https://github.com/flutter/flutter.git
[  +51 ms] executing: [C:\SDK\flutter/] git rev-parse --abbrev-ref HEAD
[  +23 ms] Exit code 0 from: git rev-parse --abbrev-ref HEAD
[        ] stable
[  +57 ms] Artifact Instance of 'AndroidGenSnapshotArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'AndroidInternalBuildArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'IOSEngineArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'FlutterWebSdk' is not required, skipping update.
[   +2 ms] Artifact Instance of 'WindowsEngineArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'MacOSEngineArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'LinuxEngineArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'FlutterRunnerDebugSymbols' is not required, skipping update.
[  +42 ms] executing: C:\Users\MTNie\AppData\Local\Android\Sdk\platform-tools\adb.exe devices -l
[  +30 ms] List of devices attached
           PMF4C17912020505       device product:WAS-LX1 model:WAS_LX1 device:HWWAS-H transport_id:2
           emulator-5554          device product:sdk_gphone_x86_arm model:AOSP_on_IA_Emulator device:generic_x86_arm transport_id:1
[   +5 ms] C:\Users\MTNie\AppData\Local\Android\Sdk\platform-tools\adb.exe -s PMF4C17912020505 shell getprop
[  +64 ms] C:\Users\MTNie\AppData\Local\Android\Sdk\platform-tools\adb.exe -s emulator-5554 shell getprop
[  +41 ms] Artifact Instance of 'AndroidInternalBuildArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'IOSEngineArtifacts' is not required, skipping update.
[   +6 ms] Artifact Instance of 'WindowsEngineArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'MacOSEngineArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'LinuxEngineArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not required, skipping update.
[        ] Artifact Instance of 'FlutterRunnerDebugSymbols' is not required, skipping update.
[  +60 ms] Multiple devices found:
[   +3 ms] ro.hardware = hi6250
[        ] ro.build.characteristics = default
[   +1 ms] ro.hardware = ranchu
[  +13 ms] WAS LX1 (mobile)             • PMF4C17912020505 • android-arm64  • Android 8.0.0 (API 26)
[   +1 ms] AOSP on IA Emulator (mobile) • emulator-5554    • android-x86    • Android 9 (API 28) (emulator)
[        ] Chrome (web)                 • chrome           • web-javascript • Google Chrome 88.0.4324.190
[        ] Edge (web)                   • edge             • web-javascript • Microsoft Edge 89.0.774.45
[   +1 ms] [1]: WAS LX1 (PMF4C17912020505)
[        ] [2]: AOSP on IA Emulator (emulator-5554)
[        ] [3]: Chrome (chrome)
[        ] [4]: Edge (edge)
```

<!--
     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 mysample...                                                   
No issues found! (ran in 1.2s)
```

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[√] Flutter (Channel stable, 2.0.1, on Microsoft Windows [Version 10.0.19041.804], locale en-DK)
    • Flutter version 2.0.1 at C:\SDK\flutter
    • Framework revision c5a4b4029c (6 days ago), 2021-03-04 09:47:48 -0800
    • Engine revision 40441def69
    • Dart version 2.12.0

[√] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at C:\Users\MTNie\AppData\Local\Android\Sdk
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = C:\Users\MTNie\AppData\Local\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 1.54.1)
    • VS Code at C:\Users\MTNie\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.20.0

[√] Connected device (4 available)
    • WAS LX1 (mobile)             • PMF4C17912020505 • android-arm64  • Android 8.0.0 (API 26)
    • AOSP on IA Emulator (mobile) • emulator-5554    • android-x86    • Android 9 (API 28) (emulator)
    • Chrome (web)                 • chrome           • web-javascript • Google Chrome 88.0.4324.190
    • Edge (web)                   • edge             • web-javascript • Microsoft Edge 89.0.774.45

• No issues found!
```

</details>