Shape is no longer honoured in a Material Widget

[kunit1]

Steps to Reproduce

Creating a Material Widget and setting the shape to StadiumBorder() does not result in the expected shape. Instead, the material simply looks like a rectangle. This used to work in the Beta channel but is broken in the Master channel

 Widget floatingBar() => Material(
    shape: StadiumBorder(),
    elevation: 3.0,
    child: Ink(
      decoration: BoxDecoration(
        gradient: LinearGradient(colors: kitGradients)),
      child: FloatingActionButton.extended(
        onPressed: () {},
        backgroundColor: Colors.transparent,
        icon: Icon(
          Icons.done,
          color: Colors.white,
        ),
        label: Text(
          "Continue",
          style: TextStyle(color: Colors.white),
        ),
      ),
    ),
  );

Screenshot of wrong output

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel master, v0.5.9-pre.29, on Microsoft Windows [Version 10.0.17134.165], locale en-CA)
[√] Android toolchain - develop for Android devices (Android SDK 28.0.0)
[√] Android Studio (version 3.1)
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
[√] VS Code, 64-bit edition (version 1.25.1)
[√] Connected devices (1 available)

• No issues found!

[kunit1]

Adding clipBehavior: Clip.antiAlias, to the Material widget solves the issue. This seems to be a recent change

[ZaynJarvis]

The issue still happens on Material Button even when set clipBehavior: Clip.antiAlias

MaterialButton(
  color: Colors.red,
  shape: StadiumBorder(),
  clipBehavior: Clip.antiAlias,
  child: Text("1"),
  onPressed: () {},
),

[github-actions]

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