解决Firefox下outerHTML不支持问题

代码很简单，如下：

var pro = window.HTMLElement.prototype;
pro.__defineGetter__("outerHTML", function(){
	var str = "<" + this.tagName;
	var a = this.attributes;
	for(var i = 0, len = a.length; i < len; i++){
		if(a[i].specified){
			str += " " + a[i].name + '="' + a[i].value + '"';
		}
	}
	if(!this.canHaveChildren){
		return str + " />";
	}
	return str + ">" + this.innerHTML + "</" + this.tagName + ">";
});
pro.__defineSetter__("outerHTML", function(s){
	var r = this.ownerDocument.createRange();
	r.setStartBefore(this);
	var df = r.createContextualFragment(s);
	this.parentNode.replaceChild(df, this);
	return s;
});
pro.__defineGetter__("canHaveChildren", function(){
	return !/^(area|base|basefont|col|frame|hr|img|br|input|isindex|link|meta|param)$/.test(this.tagName.toLowerCase());
});