Turbopack: fix sourcemaps of scopehoisted comments (#80987)
There was a bug in the source mappings for scope hoisted comments. They actually contained invalid mappings, which was only caught by the invalid mapping landing exactly on an invalid multibyte character boundary, which triggered a debug assertion:
What's happening is:
1. You do `comments.add_leading` with a `Comment` containing the real span
2. Traverse the AST and encode all bytepos in the soans
3. codegen, the bytepos in the AST are encoded, but the ones in the comments (Comment.span) are not (i.e. via `comments.take_leading`
Now, they are all consistently encoded and correctly mapped:
