Flutter - surfaceTint missing from toColorScheme

[kvanry]

Describe the bug
A clear and concise description of what the bug is.

extension MaterialSchemeUtils on MaterialScheme {
  ColorScheme toColorScheme() {
    return ColorScheme(
      ...
      // Missing surfaceTint: surfaceTint,
      ...
    )
  }
}

To Reproduce
Steps to reproduce the behavior:

1. Go to Export->Flutter (Dart)
2. Go to put generated code in app
3. Missing the above.

Expected behavior
A clear and concise description of what you expected to happen.

surfaceTint to be applied to the ColorScheme

Screenshots
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Desktop (please complete the following information):

• OS: Mac
• Browser Chrome
• Version 2.0.1

Smartphone (please complete the following information):

• Device: N/A
• OS: N/A
• Browser N/A
• Version N/A

Additional context
Add any other context about the problem here.