ilasm can't assemble vbbyrefstr parameters

[m42a]

Steps to Reproduce

1. Create the following C# file:

using System.Runtime.InteropServices;
namespace n { class C {
	[DllImport("foo")] public static extern void foo([MarshalAs(UnmanagedType.VBByRefStr)] string s);
} }

2. Compile it to a dll with mcs or csc
3. Disassemble the dll with monodis
4. Assemble the il with ilasm

Current Behavior

ilasm fails with "irrecoverable syntax error"

Expected Behavior

ilasm creates a binary equivalent to the disassembled binary

On which platforms did you notice this

[ ] macOS
[X] Linux
[ ] Windows

Version Used: 5.10.1

[marek-safar]

@kg could you look into that

[migueldeicaza]

I have a fix.