There is no way the browser was rewritten "from scratch". If it were rewritten from scratch, the issues that crashed its predecessors (like http://crashie8.com) would not also crash IE9.
Heh -- you mean to say that shitty HTML coding caused a problem in IE8. Did you even try it in IE9? I get this from crashie8.com (note -- no crash):
---
Internet Explorer has stopped trying to restore this website. It appears that the website continues to have a problem.
..and still didn't end up with Chrome.
thank god -- I wish it worked on my end, but I'm endlessly forced to empty cache in Chrome to avoid broken images, stalled scripts, etc. -- which makes it altogether unusable.