title: Custom directive v-focus is not working on vuetify component
body: <p>I'm trying to use a vuejs custom directive called focus on a component from vuetify which is <code>v-field-text</code>. </p>
  
  <pre><code>directives: {
      focus: {
        // directive definition
        inserted: function(el) {
          el.focus();
        }
      }
    }
  </code></pre>
  
  <p>I have a todo list, and my todos are printed with <code>v-for</code>, I also have an option to edit todos, whenever i click on edit button todo dispears and todo edit input apears. <br>
  I am using this focus directive to auto focusing the input. <br> <br>
  However when i use this like this is not working:</p>
  
  <pre><code>&lt;v-field-text v-focus&gt;&lt;/v-field-text&gt;
  </code></pre>
  
  <p>But it works like this:</p>
  
  <pre><code>&lt;input v-focus /&gt;
  </code></pre>
  
  <p>When i <code>console.log</code> the <code>el</code> from the directive, i see that its referring to a <code>div</code> element created by vuetify.
  How to fix this issue?</p>