Repository: flutter
Issue: Draggable zone on a transformed element is wrong.
Labels: framework,d: api docs,has reproducible steps,P2,found in release: 3.3,found in release: 3.7,team-framework,triaged-framework

When having a transformed element inside a draggable zone, the draggable zone is not transformed.

## Steps to Reproduce

Minimal example:

```
import 'dart:math' as math;

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new Align(
        alignment: FractionalOffset.center,
        child: Draggable(
          child: Transform.rotate(
            angle: math.pi / 4,
            child: Container(
              color: Colors.blue,
              height: 200.0,
              width: 400.0,
            ),
          ),
          feedback: Transform.rotate(
            angle: math.pi / 4,
            child: Container(
              color: Colors.red,
              height: 200.0,
              width: 400.0,
            ),
          ),
        ),
      ),
    );
  }
}
```
![transformed](https://user-images.githubusercontent.com/5709489/66023171-a69b7280-e4f0-11e9-8598-5c04675c102f.jpeg)

## Logs
<!--
     Run `flutter analyze` and attach any output of that command below.
     If there are any analysis errors, try resolving them before filing this issue.
-->

```
flutter analyze
Analyzing transform_draggable...                                        
No issues found! (ran in 1.4s)

```

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
 flutter doctor -v
[✓] Flutter (Channel beta, v1.9.1+hotfix.4, on Mac OS X 10.14.6 18G87, locale en-CH)
    • Flutter version 1.9.1+hotfix.4 at /Users/thomasfrick/development/flutter
    • Framework revision cc949a8e8b (4 days ago), 2019-09-27 15:04:59 -0700
    • Engine revision b863200c37
    • Dart version 2.5.0

 
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    • Android SDK at /Users/thomasfrick/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-28, build-tools 28.0.3
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 10.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 10.3, Build version 10G8
    • CocoaPods version 1.7.5

[✓] Android Studio (version 3.4)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 38.1.1
    • Dart plugin version 183.6270
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)

[✓] IntelliJ IDEA Ultimate Edition (version 2019.2.3)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 39.0.5
    • Dart plugin version 192.6817.14

[✓] Connected device (1 available)
    • iPhone Xʀ • 9D105B73-37E4-492B-B4F0-54DD490C2F15 • ios •
      com.apple.CoreSimulator.SimRuntime.iOS-12-4 (simulator)
```