title: Return confirm cancel button not working
body: <p>I have this link in twig  :</p>
  
  <pre><code>&lt;a href="{{ path('relation-delete', {'id': c.getCustomerId}) }}" 
     onclick="return confirm('{% trans %}relation.delete{% endtrans %}');"
     class="tip" data-original-title="Verwijder klant {{ c.getCustomerName }}"&gt;
  </code></pre>
  
  <p>The HTML in the source :</p>
  
  <pre><code>&lt;a href="/app_dev.php/projects/delete/1" class="tip" 
    data-original-title="Verwijder project Lantaarn plaatsen" 
    onclick="return confirm('Verwijderen');"&gt;
  
  &lt;button class="btn btn-danger"&gt;&lt;i class="fa fa-times fa-fw"&gt;&lt;/i&gt;&lt;/button&gt;&lt;/a&gt;`
  </code></pre>
  
  <p>the onlick confirm cancel button doesn't cancel the action but just keeps going. 
  Somebody knows what's wrong with this return confirm ?</p>