title: paper-icon-button doesn't show the icon
body: <p>Hello, I have an application where I want to use paper-icon-button, I'm using a theme Dark [Theme][1], the problem is that I'm not able to make the paper-icon-button to show the icon.</p>
  
  <h2>Imports:</h2>
  
  <pre><code>&lt;link rel="import" href="../bower_components/iron-iconset-svg/iron-iconset-svg.html"&gt;
  &lt;link rel="import" href="../bower_components/iron-iconset/iron-iconset.html"&gt;
  &lt;link rel="import" href="../bower_components/iron-icons/iron-icons.html"&gt;
  &lt;link rel="import" href="../bower_components/iron-icons/editor-icons.html"&gt;
  &lt;link rel="import" href="../bower_components/iron-icons/communication-icons.html"&gt;
  &lt;link rel="import" href="../bower_components/iron-icons/notification-icons.html"&gt;
  &lt;link rel="import" href="../bower_components/iron-icons/maps-icons.html"&gt;
  &lt;link rel="import" href="../bower_components/iron-icons/social-icons.html"&gt;
  &lt;link rel="import" href="../bower_components/iron-icon/iron-icon.html"&gt;
  &lt;!-- Paper elements --&gt;
  &lt;link rel="import" href="../bower_components/paper-icon-button/paper-icon-button.html"&gt;
  </code></pre>
  
  <h2>Element:</h2>
  
  <pre><code>&lt;dom-module id="my-adminwork"&gt;
    &lt;template&gt;
      &lt;style&gt;
        :host {
          display: block;
        },
      &lt;/style&gt;
      &lt;iron-localstorage name="my-signasafe-storage" id="localStorage_id" value="{{sessionObject}}"&gt;&lt;/iron-localstorage&gt;
      &lt;span&gt;Text example&lt;/span&gt;
      &lt;paper-icon-button icon="refresh"&gt;&lt;/paper-icon-button&gt;
    &lt;/template&gt;
  </code></pre>
  
  <p>The paper-icon-button supposed to be compound of an iron-icon element that inside have the svg icon, when I checked in the html in the browser I don't see the svg icon code inside the iron-icon element.</p>
  
  <p>Any idea of why is this happening?</p>