Shadows overview sample in gallery crashes under Windows App SDK

### Describe the bug

When running the gallery with the Wasdk head on the latest `main` commit, the 'Shadows overview' sample will crash the app:

Exception message:
> Specified cast is not valid.

Stack trace:
```
at WinRT.ExceptionHelpers.g__Throw|38_0(Int32 hr)
at ABI.Microsoft.UI.Xaml.IFrameworkElementOverridesMethods.MeasureOverride(IObjectReference _obj, Size availableSize)
at Microsoft.UI.Xaml.FrameworkElement.MeasureOverride(Size availableSize)
at Microsoft.UI.Xaml.FrameworkElement.Microsoft.UI.Xaml.IFrameworkElementOverrides.MeasureOverride(Size availableSize)
at ABI.Microsoft.UI.Xaml.IFrameworkElementOverrides.Do_Abi_MeasureOverride_0(IntPtr thisPtr, Size availableSize, Size* result)
```

This behavior is not present when running the gallery under UWP.

### Steps to reproduce

```text
1. Clone the repo
2. Generate the gallery solution, include the Media component and the wasdk multitarget/head.
3. Build and deploy the wasdk gallery
4. Navigate to the 'Shadows overview' sample page and observe crash.
```

### Expected behavior

No crash

### Screenshots

_No response_

### Code Platform

- [ ] UWP
- [X] WinAppSDK / WinUI 3
- [ ] Web Assembly (WASM)
- [ ] Android
- [ ] iOS
- [ ] MacOS
- [ ] Linux / GTK

### Windows Build Number

- [ ] Windows 10 1809 (Build 17763)
- [ ] Windows 10 1903 (Build 18362)
- [ ] Windows 10 1909 (Build 18363)
- [ ] Windows 10 2004 (Build 19041)
- [ ] Windows 10 20H2 (Build 19042)
- [ ] Windows 10 21H1 (Build 19043)
- [ ] Windows 10 21H2 (Build 19044)
- [ ] Windows 10 22H2 (Build 19045)
- [ ] Windows 11 21H2 (Build 22000)
- [ ] Other (specify)

### Other Windows Build number

_No response_

### App minimum and target SDK version

- [ ] Windows 10, version 1809 (Build 17763)
- [ ] Windows 10, version 1903 (Build 18362)
- [ ] Windows 10, version 1909 (Build 18363)
- [ ] Windows 10, version 2004 (Build 19041)
- [ ] Windows 10, version 2104 (Build 20348)
- [ ] Windows 11, version 22H2 (Build 22000)
- [ ] Other (specify)

### Other SDK version

_No response_

### Visual Studio Version

_No response_

### Visual Studio Build Number

_No response_

### Device form factor

_No response_

### Additional context

_No response_

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