JS library to simulate Internet Explorer?

There are some JS library to simulate the IE in Webkit? For instance: IE8 doesn't support border-radius currently (maybe on IE10). So I run a JS library that check if I'm using the border-radius then remove it to make similar to IE vision.

It's a crazy idea, I know, but work on IE is too slow, and if I can simulate it on Webkit, will be great! I need do it to an own project too.

Note: I know that exists a Chrome extension to make a IE tab, but the proposal is different: I need run on Webkit, but eliminating features not supported on IE.

Edit1: I'm working on a Webkit based IDE to developer HTML templates. Basically I need a button that emulate the IE view version without need a IE installed too (Mac, Linux for instance). Will be interesting have a Mozilla emulator too, for instance. Basically I will generate a CSS file to each browser too. For instance: -webkit properties not will be included to MSIE CSS. filter not will be included in Webkit CSS (but can be emulated).

So, I'll make a copy of current HTML page before apply a JS method that will edit or delete the unsupported content, make it similar to IE. If IE8 not support border-radius, it'll be removed and I'll see basically an IE version of page. If Mozilla not support -webkit-box-sizing it will be renamed to -moz-box-sizing if disponible.

I know of no script, and frankly I don't expect to see one any time soon as the task of re-creating the topography of IE's support for CSS in various versions of the browser would be a massive undertaking. It would further complicate things if the undocumented hacks like _height were supported too.

Frankly, the best way to test your site in IE8 is to use IE8+. In versions IE8 and up Microsoft introduced Browser Emulation, permitting you to fallback and emulate any number of IE versions all from a single browser - I use this daily, and it's a fantastic feature.

Within IE, open up the Developer Tools by pressing F12 and from there you can change the Browser Mode to IE8. No refresh will be necessary as the browser will handle that on its own. Using this method you can quickly test versions 7 through 10 (assuming you're testing from IE10) with the click of a button.

Disabling CSS3

If all you would like to do is disable CSS3 features, you can use the Strip Tease bookmarklet. It's not a fully-developed solution, so keep in mind that it won't handle things like advanced selectors, etc.