title: Correct usage of content tag inside PolymerElements
body: <p>So I decided that its better to separate Filter from my PolymerTable. I created a PolymerElement for my Filter. I want to show a part of the Table inside the FilterElement, since it should be displayed as a Bootstrap panel with a table.
  <a href="http://getbootstrap.com/components/#panels-tables" rel="nofollow">http://getbootstrap.com/components/#panels-tables</a>
  I'm not sure if I use the content tag right or if thats even possible what im trying.
  My Code looks a bit like this:</p>
  
  
  
  <pre class="lang-dart prettyprint-override"><code>&lt;!-- index.html --&gt;
  &lt;!-- ... --&gt;
  &lt;poly-table&gt;&lt;/poly-table&gt;
  &lt;!-- ... --&gt;
  </code></pre>
  
  
  
  <pre class="lang-dart prettyprint-override"><code>&lt;!-- poly-table.html --&gt;
  &lt;polymer-element name="poly-table"&gt;
   &lt;template&gt;
    /* style */
    &lt;div id="table_cont"&gt;
     &lt;poly-filter&gt;
      &lt;table class="table"&gt;
        /* ... stuff inside ... */
      &lt;/table&gt;
     &lt;/poly-filter&gt;
    &lt;/div&gt;
   &lt;/template&gt;
  &lt;/polymer-element&gt;
  </code></pre>
  
  
  
  <pre class="lang-dart prettyprint-override"><code>&lt;!-- poly-filter.html --&gt;
  &lt;polymer-element name="poly-filter"&gt;
   &lt;template&gt;
    /* style */
    &lt;div id="filter_cont" class="panel"&gt;
     &lt;div class="panel-heading"&gt;
       Filter
     &lt;/div&gt;
     &lt;div class="panel-body&gt;
       &lt;!-- Filter Content here --&gt;
     &lt;/div&gt;
     &lt;content&gt;&lt;/content&gt;
    &lt;/div&gt;
   &lt;/template&gt;
  &lt;/polymer-element&gt;
  </code></pre>
  
  <p>My Table will get rendered outside and above my filter instead of under the Filter...</p>
  
  <p>I override <code>parseDeclaration</code> in <code>PolyFilter</code> so the <code>&lt;poly-filter&gt;</code> element gets rendered in the light DOM. </p>
  
  <pre class="lang-dart prettyprint-override"><code>parseDeclaration(elementElement) {
    var template = fetchTemplate(elementElement);
    if (template != null) {
      lightFromTemplate(template);
    } 
  }
  </code></pre>