[0.8] template x-repeat throws error under native ShadowDOM

[frankiefu]

The following code when run under native ShadowDOM will cause error: Uncaught TypeError: Cannot read property 'debounce' of undefined x-repeat.html:139

<dom-module id="x-app">

  <template>

    <template is="x-repeat" items="[[items]]">
      <div>[[item.name]]</div>
    </template>

  </template>

</dom-module>

<script>

  Polymer({

    is: 'x-app',

    configure: function() {
      return {
        items: [{name: 'foo'}, {name: 'bar'}, {name: 'zot'}]
      }
    }

  });

</script>

[sorvell]

Fixed via 7c7e426