Repository: flutter
Issue: Interaction between DataTable and TableRowInkWell is not well described
Labels: framework,f: material design,d: api docs,team-design,triaged-design

## Steps to Reproduce

```dart
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  void alert() {
    showAboutDialog(context: context);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: DataTable(
          columns: [
            DataColumn(label: Text('Col 1')),
            DataColumn(label: Text('Col 2')),
          ],
          rows: [
            DataRow(cells: [
              DataCell(
                TableRowInkWell(
                  child: Container(color: Colors.red, child: Text('Val 1')),
                ),
                onTap: alert,
              ),
              DataCell(TableRowInkWell(
                child: Container(color: Colors.red, child: Text('Val 2')),
                onTap: alert,
              )),
            ])
          ],
        ),
      ),
    );
  }
}
```

Also please see this video:

[![IMAGE ALT TEXT HERE](https://img.youtube.com/vi/bXYR8qOZ6ac/0.jpg)](https://www.youtube.com/watch?v=bXYR8qOZ6ac)

**Expected results:** 

Please notice the subtle difference. On the first column I'm using the `onTap` on the `DataCell` and on the second column on the `TableRowInkWell`. 
If you see the video (or run the code) you will notice how on the the first column the `onTap` works as expected, tapping anywhere on the cell. BUT, the InkWell is limited to that cell alone. Bad UI.

On the second column, the InkWell expands to the whole row (as expected by the `TableRowInkWell`) BUT, if you tap OUTSIDE of the actual content (red background) the tap never registers. You have to tap right on top of it for it to work. 

**Actual results:**

`onTap` should work when you tap anywhere on the row. 

<details>
  <summary>Logs</summary>


<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[✓] Flutter (Channel dev, 1.25.0-8.0.pre, on macOS 11.1 20C69
    darwin-x64, locale en-US)
    • Flutter version 1.25.0-8.0.pre at /Users/jan/flutter
    • Framework revision a12e2a473a (2 weeks ago), 2020-12-08 23:13:04
      -0500
    • Engine revision df39e5c515
    • Dart version 2.12.0 (build 2.12.0-133.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version
    29.0.3)
    • Android SDK at /Users/jan/Library/Android/sdk
    • Platform android-R, build-tools 29.0.3
    • 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-b3-6915495)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 12.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.3, Build version 12C33
    • CocoaPods version 1.10.0

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google
      Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Applications/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)

[✓] VS Code (version 1.52.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension can be installed from:
      🔨
      https://marketplace.visualstudio.com/items?itemName=Dart-Code.flut
      ter

[✓] Connected device (4 available)
    • iPhone de Jan Lubeck (mobile) •
      d167f1a8b5eed7cd0312f630a2da37135e6788f3 • ios            • iOS
      14.2
    • iPhone 12 mini (mobile)       •
      B322F835-BB5C-4C50-9B15-AB3F8D348BD0     • ios            •
      com.apple.CoreSimulator.SimRuntime.iOS-14-3 (simulator)
    • macOS (desktop)               • macos
      • darwin-x64     • macOS 11.1 20C69 darwin-x64
    • Chrome (web)                  • chrome
      • web-javascript • Google Chrome 87.0.4280.88
    ! Error: iPhone de Jan Lubeck is busy: Copying cache files from
      device. Xcode will continue when iPhone de Jan Lubeck is finished.
      (code -10)

• No issues found!
```

</details>