Creates a stylesheet from a text blob of rules.
These rules will be wrapped in a STYLE tag and appended to the HEAD of the document.
@param {String} cssText The text containing the css rules
@param {String} id An id to add to the stylesheet for later removal
@return {CSSStyleSheet}
function(cssText, id) {
            var ss,
                head = doc.getElementsByTagName("head")[0],
                styleEl = doc.createElement("style");

            styleEl.setAttribute("type", "text/css");
            if (id) {
               styleEl.setAttribute("id", id);
            }

            if (Ext.isIE) {
               head.appendChild(styleEl);
               ss = styleEl.styleSheet;
               ss.cssText = cssText;
            } else {
                try{
                    styleEl.appendChild(doc.createTextNode(cssText));
                } catch(e) {
                   styleEl.cssText = cssText;
                }
                head.appendChild(styleEl);
                ss = styleEl.styleSheet ? styleEl.styleSheet : (styleEl.sheet || doc.styleSheets[doc.styleSheets.length-1]);
            }
            CSS.cacheStyleSheet(ss);
            return ss;
        }