Make sure all of the calculations of enregistered return types match correctly. ...

Make sure all of the calculations of enregistered return types match correctly. (dotnet/coreclr#24771)

* Make sure all of the calculations of enregistered return types match correctly.

* Revert "Disable ARM64 IDispatch tests (dotnet/coreclr#24770)"

This reverts commit dotnet/coreclr@852f40d5f1a3cff4d381c2de2d2a86fe8b1f29b4.

Commit migrated from https://github.com/dotnet/coreclr/commit/83309575a1552e39fe505cbd883391f3dcbea8b4