title: Performance of setting img src to unchanged value?
body: <p>If I have an img tag like</p>
  
  <pre><code>&lt;img src="example.png" /&gt;
  </code></pre>
  
  <p>and I set it via</p>
  
  <pre><code>myImg.src = "example.png";
  </code></pre>
  
  <p>to the same value again, will this be a no-op, or will browsers unnecessarily redraw the image? (I'm mainly interested in the behaviour of IE6-8, FF3.x, Safari 4-5 and Chrome.)</p>
  
  <p>I need to change many (hundreds of) images at once, and manually comparing the src attribute might be a little bit superfluous - as I assume, that the browser already does this for me?</p>