pandoc-2.8: test/command/5797.md

```
% pandoc -f html -t html
<mark>Ctrl-C</mark>
^D
<mark>Ctrl-C</mark>
```

```
% pandoc -f html -t native
<mark>Ctrl-C</mark>
^D
[Plain [Span ("",["mark"],[]) [Str "Ctrl-C"]]]
```

```
% pandoc -f native -t html
[Plain [Span ("",["mark"],[]) [Str "Ctrl-C"]]]
^D
<mark>Ctrl-C</mark>
```