title: Using .numChildren() in AngularFire
body: <p>I'm trying to use <code>.numChildren()</code> in AngularFire, but not sure I'm doing it correctly.</p>
  
  <pre><code>function getServiceProviders(serviceId) {
    var serviceProviders = ref.child('services').child(serviceId).child('providers');
    return serviceProviders.numChildren();
  }
  </code></pre>
  
  <p>I'm getting the following error:</p>
  
  <pre><code>TypeError: e.numChildren is not a function
  </code></pre>
  
  <p>Not sure if this is due to me using Browserify, or I'm just trying to access <code>numChildren</code> incorrectly.</p>
  
  <p>Any help is appreciated. Thanks in advance!</p>