title: Polymer + Firebase (Polymerfire): <firebase-query> not working inside single page app view (with <firebase-app> located in my-app.html)
body: <p>I'm trying to push data to Firebase using Polymerfire and the Polymer App Toolbox template:</p>
  
  <ul>
  <li><code>my-app.html</code> contains a configured <code>&lt;firebase-app&gt;</code> component.</li>
  <li><code>my-models.html</code> (which is a page configured in <code>my-app.html</code> routes) contains a <code>&lt;add-model&gt;</code> component</li>
  <li><code>&lt;add-model&gt;</code> is a form with a <code>&lt;firebase-query&gt;</code>, <code>&lt;firebase-auth&gt;</code>, input, and submit button.</li>
  <li><p>I attempt to push data using <code>&lt;firebase-query&gt;</code> with the following function in the <code>add-model.html</code> <code>Polymer</code> object:</p>
  
  <pre><code>Polymer({
      is: 'add-model',
      properties: {
          data: {
              type: Object
          }
      },
      create: function() {
         this.$.query.ref.push({
             name: this.$.myModelName.value
          });
      }
  });
  </code></pre>
  
  <h3>Outcome</h3></li>
  <li><p>Calling <code>push</code> on the <code>&lt;firebase-query&gt;</code> object in <code>add-model.html</code> returns <code>Cannot read property 'push' of undefined</code> (<a href="https://stackoverflow.com/questions/41435694/polymer-firebase-polymerfire-cannot-read-property-push-of-undefined-th/41436543#41436543">explained in this Q/A</a>, in our case it's because <code>&lt;firebase-app&gt;</code> does not appear to be properly declared).</p></li>
  <li>Moving <code>&lt;firebase-app&gt;</code> from <code>my-app.html</code> to <code>add-model.html</code> file does make the <code>push</code> function work, but then <code>my-app.html</code> loses its Firebase functionality.</li>
  <li>Calling <code>&lt;firebase-app&gt;</code> in both my-app.html and add-model.html returns <code>Uncaught Error: Firebase App named 'firebase-app' already exists.</code></li>
  <li><code>&lt;firebase-auth&gt;</code> does work in <code>add-model.html</code> and returns a <code>[[user]]</code> object.</li>
  </ul>
  
  <p>How do I make <code>firebase-query</code> properly communicate with <code>firebase-app</code> from my route?</p>