Repository: flutter
Issue: [web] [html-renderer] [iOS-macOS-Safari] Shadow offsets are not rendered correctly
Labels: engine,platform-web,c: rendering,e: web_html,has reproducible steps,browser: safari-macos,P2,browser: safari-ios,found in release: 2.10,found in release: 2.11,team-web,triaged-web

## Steps to Reproduce

1. Use a container with a shadow that has some offset. I'm using a white container on a white background in the code example.
2. Run the web app using the HTML renderer.
3. See that it doesn't render correctly on mobile and desktop Safari. [It's fine on Chrome. So if you want to try it on desktop, copy the link from your debug Chrome instance and open it using Safari]

| Expected results | Actual results |
| -- | -- |
| <img width="497" alt="Screen Shot 2022-02-09 at 12 24 17 PM" src="https://user-images.githubusercontent.com/29583601/153287469-ddf7505f-cc91-4b0b-b722-0e7526663c13.png"> | <img width="574" alt="Screen Shot 2022-02-09 at 12 45 58 PM" src="https://user-images.githubusercontent.com/29583601/153287511-ac1ebb10-e8ab-40ea-a5ac-823c43f9edf4.png"> |

Reproducible on both iOS and macOS.

<details>
<summary>Code sample</summary>

```
import 'package:flutter/material.dart';

class ShadowTest extends StatelessWidget {
  const ShadowTest({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Material(
      color: Colors.white,
      child: Center(
        child: Container(
          width: 100,
          height: 100,
          decoration: BoxDecoration(
            color: Colors.white,
            boxShadow: [
              BoxShadow(
                color: Colors.black26,
                // This is not rendered correctly on the mobile browsers.
                offset: Offset(15, 15),
                blurRadius: 40,
              ),
            ],
            borderRadius: BorderRadius.circular(30),
          ),
        ),
      ),
    );
  }
}

```

</details>

<details>
  <summary>Logs</summary>

No logs were found between backlits after running `flutter run --verbose`.
No analysis errors were found after running `flutter analyze`.

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
[✓] Flutter (Channel stable, 2.10.0, on macOS 12.1 21C52 darwin-x64, locale en-US)
    • Flutter version 2.10.0 at /Users/behnamsattar/tools/bin/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 5f105a6ca7 (8 days ago), 2022-02-01 14:15:42 -0800
    • Engine revision 776efd2034
    • Dart version 2.16.0
    • DevTools version 2.9.2

[!] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Users/behnamsattar/Library/Android/sdk
    ✗ cmdline-tools component is missing
      Run `path/to/sdkmanager --install "cmdline-tools;latest"`
      See https://developer.android.com/studio/command-line for more details.
    ✗ Android license status unknown.
      Run `flutter doctor --android-licenses` to accept the SDK licenses.
      See https://flutter.dev/docs/get-started/install/macos#android-setup for more details.

[✓] Xcode - develop for iOS and macOS (Xcode 13.2.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • CocoaPods version 1.11.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2020.3)
    • 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 11.0.10+0-b96-7281165)

[✓] VS Code (version 1.64.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.34.0

[✓] Connected device (1 available)
    • Chrome (web) • chrome • web-javascript • Google Chrome 98.0.4758.80

[✓] HTTP Host Availability
    • All required HTTP hosts are available
```

</details>