Repository: flutter
Issue: NestedScrollView in DraggableScrollableSheet not working
Labels: framework,f: scrolling,has reproducible steps,P2,found in release: 3.7,found in release: 3.10,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. Run `flutter create bug`.
2. Update the files as follows: 
```dart
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

void main() => runApp(
      const CupertinoApp(
        title: 'Flutter Demo',
        home: const MyPage(),
      ),
    );

class MyPage extends StatelessWidget {
  const MyPage({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) => ColoredBox(
        color: Colors.red,
        child: DraggableScrollableSheet(
          builder: (BuildContext context, ScrollController scrollController) =>
              NestedScrollView(
            controller: scrollController,
            headerSliverBuilder:
                (BuildContext context, bool innerBoxIsScrolled) => [
              SliverToBoxAdapter(
                child: ColoredBox(
                  color: Colors.yellow,
                  child: Center(
                    child: RotatedBox(
                      quarterTurns: 1,
                      child: Text('Test ' * 3),
                    ),
                  ),
                ),
              ),
            ],
            body: CustomScrollView(
              slivers: [
                SliverList(
                  delegate: SliverChildBuilderDelegate(
                    (context, index) => ColoredBox(
                      color: index.isEven ? Colors.green : Colors.blue,
                      child: const SizedBox(
                        height: 100,
                      ),
                    ),
                  ),
                ),
              ],
            ),
          ),
        ),
      );
}
```
3. 
![example](https://user-images.githubusercontent.com/16593680/90654638-423ceb00-e249-11ea-95cc-f493c4310834.gif)


**Expected results:** 
Fix NestedScrollView or DraggableScrollableSheet.
Or how to nest SliverList in SliverList?

**Actual results:** NestedScrollView is fine for my application, but it doesn't work with DraggableScrollableSheet.

<details>
  <summary>Logs</summary>

```
[✓] Flutter (Channel stable, 1.20.2, on Mac OS X 10.15.6 19G73, locale en-BY)
    • Flutter version 1.20.2 at /Users/nikitadold/development/flutter
    • Framework revision bbfbf1770c (6 days ago), 2020-08-13 08:33:09 -0700
    • Engine revision 9d5b21729f
    • Dart version 2.9.1

 
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.0)
    • Android SDK at /Users/nikitadold/Library/Android/sdk
    • Platform android-30, build-tools 30.0.0
    • Java binary at: /Users/nikitadold/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/193.6626763/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 11.6)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.6, Build version 11E708
    • CocoaPods version 1.9.3

[!] Android Studio (version 4.0)
    • Android Studio at /Users/nikitadold/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/193.6626763/Android Studio.app/Contents
    ✗ Flutter plugin not installed; this adds Flutter specific functionality.
    ✗ Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)

[✓] IntelliJ IDEA Ultimate Edition (version 2020.2)
    • IntelliJ at /Users/nikitadold/Applications/JetBrains Toolbox/IntelliJ IDEA Ultimate.app
    • Flutter plugin version 48.1.4
    • Dart plugin version 202.6397.47

[✓] Connected device (1 available)
    • Pixel 4 (mobile) • 192.168.2.6:5555 • android-arm64 • Android 10 (API 29)

! Doctor found issues in 1 category.
```

</details>