Incorrect syntax coloring in interface definition

From https://github.com/OmniSharp/omnisharp-vscode/issues/3201

```cs
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Runtime.InteropServices;

internal partial class Interop
{
internal partial class Mshtml
{
public interface IHTMLElement2
{
[return: MarshalAs(UnmanagedType.Interface)]
IHTMLElement
InsertAdjacentElement(string @where,
[In, MarshalAs(UnmanagedType.Interface)] IHTMLElement insertedElement);
[return: MarshalAs(UnmanagedType.Interface)]
IHTMLElement
applyElement([In, MarshalAs(UnmanagedType.Interface)] IHTMLElement apply,
string @where);
}
}
}
```

Notice that the coloring of the parameters is incorrect

Removing the newline corrects it:

See https://github.com/dotnet/winforms/pull/1533