Steps to reproduce:
1. Download 1104540_repro.zip
2. Switch platform to UWP
3. Set build type to XAML
4. Build a "test" scene on IL2CPP backend
5. Open Visual Studio and build the solution (Debug, x64, Local machine)
6. Click on the button

Expected results: Two pop-ups show up
Actual results: One pop-up show up other throws an exception

Reproduced with: 2019.1.0a12, 2018.3.0f1, 2018.2.20f1, 2017.4.17f1

Note: Not reproducible with .NET backend
Exception:
InvalidCastException: Specified cast is not valid.
at Windows.UI.Xaml.Controls.ContentControl.put_Content (System.Object value) [0x00000] in <00000000000000000000000000000000>:0
at Test..ctor () [0x00000] in <00000000000000000000000000000000>:0
at System.Runtime.CompilerServices.AsyncMethodBuilderCore+MoveNextRunner.InvokeMoveNext (System.Object stateMachine) [0x00000] in <00000000000000000000000000000000>:0
at System.Threading.ContextCallback.Invoke (System.Object state) [0x00000] in <00000000000000000000000000000000>:0
at System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in <00000000000000000000000000000000>:0
at System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) [0x00000] in <00000000000000000000000000000000>:0