The issue with the current code is that comments are collapsed, so comments like
the one from the test end up in a string like:
```
"// this is a single line comment\n/* block = */"
```
I chose to fix it by detecting whether we're in a block comment starting from
the end instead, and tested a single-line comment ended in `*/` just for sanity,
ensuring line breaks are not removed in that case, which would break the
formatting.
The right fix eventually is probably to lex the comments properly, but this does
the work for now, I guess :)
Fixes#3025
66c15e46ba