Markup block - Gen<None> - 11 - (0:0,0)
    HtmlComment block - Gen<None> - 10 - (0:0,0)
        Markup span - Gen<Markup> - [<!--] - SpanEditHandler;Accepts:None - (0:0,0) - Tokens:3
            SyntaxKind.OpenAngle;[<];
            SyntaxKind.Bang;[!];
            SyntaxKind.DoubleHyphen;[--];
        Markup span - Gen<Markup> - [Foo] - SpanEditHandler;Accepts:Whitespace - (4:0,4) - Tokens:1
            SyntaxKind.Text;[Foo];
        Markup span - Gen<Markup> - [-->] - SpanEditHandler;Accepts:None - (7:0,7) - Tokens:2
            SyntaxKind.DoubleHyphen;[--];
            SyntaxKind.CloseAngle;[>];
    Markup span - Gen<Markup> - [ ] - SpanEditHandler;Accepts:None - (10:0,10) - Tokens:1
        SyntaxKind.Whitespace;[ ];
