Apart from that one there is an old IE proprietary format just as there are other old proprietary format for eg NS 4.x.
In short, all JS browsers have a DOM of some sort.
If you can't get your JS to work in Netscape 6+ it's generally becuse you are stuck in the late 1990-ies coding with a browserspecific proprietary DOM instead of a modern one that works crossbrowser.
In any case, your page linebreaks just fine in IE 6.01 when I tried it.
However it will only linebreak if there actually IS somewhere to linebreak (that means a space). If you have 200 chars in one row and no space the row will be minimum 200 chars long.
The reason i suggested textarea before is that IE has a special property in were it actually makes linebreaks even in compact (no space) text if entered in textareas.