title: Layout Attribute not working
body: <p>I'm probably doing something stupidly wrong. I'm using <code>Polymer 1.0</code> and trying to make a very basic module. But when I specify the <code>Layout Attributes</code> they won't work. However, if I type <code>class="layout flex [etc..]"</code> and so on, it will work. See below:</p>
  
  <pre><code>&lt;script src="bower_components/webcomponentsjs/webcomponents.min.js"&gt;&lt;/script&gt;
  &lt;script src="bower_components/time-elements/time-elements.js"&gt;&lt;/script&gt;
  &lt;link rel="import" href="/bower_components/polymer/polymer.html"&gt;
  
  &lt;dom-module id="x-chat-list"&gt;
  &lt;template&gt;
      &lt;section class="user-list" layout horizontal&gt;
          &lt;div class="avatar {{color}}" style="background-image: url({{avatar}})"&gt;
              &lt;div class="status {{status}}"&gt;&lt;/div&gt;
          &lt;/div&gt;
          &lt;div flex&gt;
              &lt;div class="username"&gt;{{username}}&lt;/div&gt;
              &lt;div class="text"&gt;{{text}}&lt;/div&gt;
          &lt;/div&gt;
          &lt;time class="timestamp" is="relative-time" datetime="{{timestamp}}"&gt;&lt;/time&gt;
      &lt;/section&gt;
  &lt;/template&gt;
  
  &lt;script&gt;
  Polymer({
          is: 'x-chat-list',
          properties: {
              avatar: '',
              color: '',
              username: '',
              text: '',
              status: '',
              timestamp: new Date().toISOString()
          }
  });
  &lt;/script&gt;
  &lt;/dom-module&gt;
  </code></pre>
  
  <p>It's as if it doesn't recognize Polymer or something.</p>
  
  <p>Thank you!</p>