title: How to querySelector elements of an element's DOM using Polymer
body: <p>I have my element :</p>
  
  <pre><code>&lt;dom-module id="x-el"&gt;
    &lt;p class="special-paragraph"&gt;first paragraph&lt;/p&gt;
    &lt;content&gt;&lt;/content&gt;
  &lt;/dom-module&gt;
  </code></pre>
  
  <p>and I use it like</p>
  
  <pre><code>&lt;x-el&gt;
    &lt;p class="special-paragraph"&gt;second paragraph&lt;/p&gt;
  &lt;/x-el&gt;
  </code></pre>
  
  <p>in my imperative part:</p>
  
  <pre><code>Polymer({
    is: 'x-el',
  
    ready: function () {
      /* this will select all .special-paragraph in the light DOM
         e.g. 'second paragraph' */
      Polymer.dom(this).querySelectorAll('.special-paragraph');
  
      /* this will select all .special-paragraph in the local DOM
         e.g. 'first paragraph' */
      Polymer.dom(this.root).querySelectorAll('.special-paragraph');
  
      /* how can I select all .special-paragraph in both light DOM and
         local DOM ? */
    }
  });
  </code></pre>
  
  <p>Is it possible to do that using Polymer built-in's ?
  Or should I use the default DOM api ?</p>