Fontsize escapes from \marginpar

The text "Goodbye" is in \tiny size with LaTeXML but not in luaLaTeX:

```
\documentclass{article}
\begin{document}
Hello
\marginpar{\tiny Comment}
Goodbye
\end{document}
```


The bug is avoided with the below
```
\documentclass{article}
\begin{document}
Hello
\marginpar{{\tiny Comment}}
Goodbye
\end{document}
```
