Using image.complete to find if image is cached on chrome?

I've rewritten your code in plain JavaScript, to make it more independent on jQuery. The core functionality hasn't changed. Fiddle: http://jsfiddle.net/EmjQG/2/

function cached(url){
    var test = document.createElement("img");
    test.src = url;
    return test.complete || test.width+test.height > 0;
}
var base_url = "http://www.google.com/images/srpr/nav_logo80.png"
alert("Expected: true or false\n" +
      cached(base_url)
      + "\n\nExpected: false (cache-busting enabled)\n" +
      cached(base_url + "?" + new Date().getTime()));
//false = not cached, true = cached

The first time, I get false and false. After I run the code again, I get true and false.