Polyfill for Object.getPrototypeOf

Object.getPrototypeOf.js

if (typeof Object.getPrototypeOf != "function")(function(){
	
	Object.getPrototypeOf =
		(typeof "".__proto__ == "object")
		? function(object){
			return getPrototypeValue(object, '__proto__');
		}
		: function(object){
			return getPrototypeValue(object, 'constructor').prototype;
		}
	;
	
	var hasOwnProperty = Object.prototype.hasOwnProperty;
	
	function getPrototypeValue(object, propertyName){
		try{
			if (hasOwnProperty.call(object, propertyName)){
				var ownValue = object[propertyName];
				delete object[propertyName];
			}
			return object[propertyName];
		}
		catch(e){throw e}
		finally{
			object[propertyName] = ownValue;
		}
	}
	
}());

How about this

if (typeof Object.getPrototypeOf === 'undefined') {
    Object.getPrototypeOf = function (obj) {
        var t = typeof obj;
        if (!obj || (t !== 'object' && t !== 'function')) {
            throw new TypeError('not and object');
        }
        return obj.__proto__;
    };
}