[jQuery] the implementation of jQuery.boxModel

[Keeper]

in jq-1.2.5,

        jQuery.boxModel = !jQuery.browser.msie || document.compatMode
== "CSS1Compat"

but in jq-1.3.2,

        jQuery(function(){
                var div = document.createElement("div");
                div.style.width = div.style.paddingLeft = "1px";

                document.body.appendChild( div );
                jQuery.boxModel = jQuery.support.boxModel = div.offsetWidth === 
2;
                document.body.removeChild( div ).style.display = 'none';
        });

I wanna know why the implementation of jQuery.boxModel changed?