title: Select is not updating when ng-model is changed
body: <p>I have code like this:</p>
  
  <pre><code>  &lt;select ng-model="mode" ng-init="mode=10"&gt;
      &lt;optgroup label="Serif"&gt;
        &lt;option value="0"&gt;Normal&lt;/option&gt;
        &lt;option value="1"&gt;Bold&lt;/option&gt;
        &lt;option value="2"&gt;Italic&lt;/option&gt;
        &lt;option value="3"&gt;Bold Italic&lt;/option&gt;
      &lt;/optgroup&gt;
      &lt;optgroup label="Sans"&gt;
        &lt;option value="4"&gt;Normal&lt;/option&gt;
        &lt;option value="5"&gt;Bold&lt;/option&gt;
        &lt;option value="6"&gt;Italic&lt;/option&gt;
        &lt;option value="7"&gt;Bold Italic&lt;/option&gt;
      &lt;/optgroup&gt;
      &lt;optgroup label="Script"&gt;
        &lt;option value="8"&gt;Normal&lt;/option&gt;
        &lt;option value="9"&gt;Bold&lt;/option&gt;
      &lt;/optgroup&gt;
      &lt;optgroup label="Fraktur"&gt;
        &lt;option value="10"&gt;Normal&lt;/option&gt;
        &lt;option value="11"&gt;Bold&lt;/option&gt;
      &lt;/optgroup&gt;
      &lt;optgroup label="Monospace"&gt;
        &lt;option value="12"&gt;Normal&lt;/option&gt;
      &lt;/optgroup&gt;
      &lt;optgroup label="Double-struck"&gt;
        &lt;option value="13"&gt;Bold&lt;/option&gt;
      &lt;/optgroup&gt;
    &lt;/select&gt;
    &lt;label for="text"&gt;Input Text&lt;/label&gt;
    &lt;input id="text" ng-model="input"/&gt;
    &lt;div&gt;
      Output: {{input|convert:mode}}
    &lt;/div&gt;
  </code></pre>
  
  <p>the mode scope value is changed, convert filter is executed with mode == 10 but the select is not update it still unselected. How can I fix select to be updated when scope variable change? </p>
  
  <p>Here is <a href="http://codepen.io/jcubic/pen/ENQWZg" rel="nofollow noreferrer">code pen</a> that demonstrate the problem.</p>