a couple of questions on threads-xform

[bushuyev]

sorry, no 'concise summary', but hopefully can be interesting for others

1. There is a comment on run saying that

All data segments are switched to "passive" data segments to ensure they're only initialized once (coming later)

but I can't find anywhere Data.kind being set to Passive (there were some lines but they're removed), there is also
assert!(mem.data_segments.is_empty() is it about same data segments? Is it now assumed that there should never be any and the comment is just old?

2. Wasm runtime spec seems to say that it manages stack itself, do I understand correctly that inject_start is to arrange for ‘rust own stack’, the one which is kept in global.get $__stack_pointer and managed by same global allocator as the rest of linear memory?

Also, it looks like inject_start doesn't actually inject it since it doesn't call builder.finish if there is no prev_start