title: canvas, drawImage does not work for remote picture
body: <p>I want to draw a picture from web, so I have the following html5 code, that's the example from  W3C Shool, but when I load the html page in Chrome, the image was displayed.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
      &lt;body&gt;
          &lt;canvas id="myCanvas" width="500" height="500" style="border:1px solid #c3c3c3;"&gt;
              Your browser does not support the canvas element.
          &lt;/canvas&gt;
  
          &lt;script type="text/javascript"&gt;
              var c=document.getElementById("myCanvas");
              var cxt=c.getContext("2d");
              var img=new Image();
              img.src='http://www.w3school.com.cn/i/ct_html5_canvas_image.gif';
              cxt.drawImage(img, 0, 0);
          &lt;/script&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>The image is from w3school, I can view it in my Chrome, my Chrome is the latest version, so I don't know where the problem is, I even try to download the picture to my local machine and place it in the same directory of the html page above, change the code to img.src='flower.gif', but it still not working. </p>