如何在聚合物2中的重复dom中添加槽

<template id="itemTemplate">
  <div class="item">
    <slot name="content"></slot>
  </div>
</template>

Polymer({
  is: 'parent-component',
  properties: {
    items: {
      type: Array,
      value: function() {
        return ['Item 1', 'Item 2', 'Item 3'];
      }
    }
  },
  ready: function() {
    var template = Polymer.Dom(this).querySelector('#itemTemplate');
    var container = Polymer.Dom(this).querySelector('.container');
    Polymer.Dom.repeat(this.items, template, container);
  }
});

<dom-module id="child-component">
  <template>
    <style>
      .item {
        border: 1px solid black;
        padding: 10px;
        margin-bottom: 10px;
      }
    </style>
    <div class="item">
      <slot name="content"></slot>
    </div>
  </template>
  <script>
    Polymer({
      is: 'child-component'
    });
  </script>
</dom-module>

<parent-component>
  <template is="dom-repeat" items="{{items}}">
    <child-component>
      <div slot="content">Item: [[item]]</div>
    </child-component>
  </template>
</parent-component>