title: Angular Validation NG-message dont show required after submit and erase text
body: <p>This is my current validation set up for my form</p>
  
  <pre><code>&lt;ng-messages for="searchForm.$error" ng-if="searchForm.$submitted"&gt;
    &lt;ng-message when="required" class="error-message"&gt;This search field is required.&lt;/ng-message&gt;
  &lt;/ng-messages&gt;
  </code></pre>
  
  <p>and my form</p>
  
  <pre><code>&lt;form role="form" ng-submit="searchForm.$valid &amp;&amp; searchcode()" name="searchForm" novalidate&gt;
  </code></pre>
  
  <p>It works fine.</p>
  
  <p>But here is what I don't like this scenario</p>
  
  <p>1) Hit Enter on empty searchbox - > it shows the correct message "Field Is Required"</p>
  
  <p>2) Start Typing and Erase Text without hitting enter - > it shows error message again</p>
  
  <p>It's the second scenario I dont want...any ideas ?</p>