Markup block - Gen<None> - 5 - (0:0,0)
    Tag block - Gen<None> - 5 - (0:0,0)
        Markup span - Gen<Markup> - [<foo>] - SpanEditHandler;Accepts:None - (0:0,0) - Tokens:3
            SyntaxKind.OpenAngle;[<];
            SyntaxKind.Text;[foo];
            SyntaxKind.CloseAngle;[>];
