Unfinished querySelector polyfill supposed to work on IE6+

querySelector.js

// querySelectorAll polyfill
(function(window){
	var document = window.document;

	//No need to polyfill
	if(document.querySelector) {
		return;
	}

	var polyfill_querySelectorAll = function (element, selector) {
		var head = document.getElementsByTagName('head')[0],
			styleTag = document.createElement('style');
		head.appendChild(styleTag);
		element.id = element.id || 'querySelectorAll_' + (new Date().getTime());
		document.__qsaels = [];
		styleTag.styleSheet.cssText = '#' + element.id + ' ' + selector + "{x:expression(document.__qsaels.push(this))}";

		// @todo found something cleaner to force expression execution
		window.scrollBy(0, 0);

		return document.__qsaels;
	};

	var polyfill_querySelector = function(element, selector) {
		// @todo make this more bulletproof
		return querySelectorAll(element, selector)[0];
	};

	function querySelectorAll(selector){
		return polyfill_querySelectorAll.call(this, selector);
	}

	function querySelector(selector){
		return polyfill_querySelector.call(this, selector);
	}

	function addPolyfill(obj, i){
		if((i = obj.length)) {
			while(i--) {
				obj[i].querySelectorAll = querySelectorAll;
				obj[i].querySelector = querySelector;
			}
		}
		else {
			obj.querySelectorAll = querySelectorAll;
			obj.querySelector = querySelector;
		}

		return obj;
	}

	addPolyfill([document, window]);

	if('Element' in window) {
		window.Element.prototype.querySelectorAll = querySelectorAll;
		window.Element.prototype.querySelector = querySelector;
		return;
	}

	// ie < 8
	function applyPolyfill(fn) {
		var oldFn = document[fn];
		document[fn] = function(arg) {
			return addPolyfill(oldFn(arg));
		};
	}
	//Make sure we also init at domReady
	document.attachEvent('onreadystatechange', function(){
		addPolyfill(document.all);
	});
	addPolyfill(document.all);

	var hijackFn = ['getElementsByTagName', 'getElementById', 'createElement'];
	for(var fn in hijackFn) {
		applyPolyfill(hijackFn[fn]);
	}
})(this);