title: AngularJS Form Validation Directive $setValidity on element
body: <p>I'm trying to use <code>$setValidity</code> on an element in a directive.  All the examples I've found seem to set it on the controller...</p>
  
  <p>I forked a JS fiddle on Form Validation and have tried a bunch of things.  Any insights would be most appreciated:
  <a href="http://jsfiddle.net/thomporter/pmKpG/2/">http://jsfiddle.net/thomporter/pmKpG/2/</a></p>
  
  <p>In the fiddle, the <code>$setValidity</code> is called on the controller:</p>
  
  <pre><code>ctrl.$setValidity('pwd', true);
  </code></pre>
  
  <p>I'd like to do something like:</p>
  
  <pre><code>elm.$setValidity('pwd', true);
  </code></pre>
  
  <p>so that in the form I can do something like:</p>
  
  <pre><code>ng-class="{error:form.password.$error.pwd}"
  </code></pre>