无法在Material Design Lite的对话模式中插入图像

<!-- 引入 MDL 的样式和脚本 -->
<link rel="stylesheet" href="https://code.getmdl.io/1.3.0/material.indigo-pink.min.css">
<script src="https://code.getmdl.io/1.3.0/material.min.js"></script>

<!-- 创建一个对话框 -->
<dialog class="mdl-dialog">
  <div class="mdl-dialog__content">
    <!-- 在对话框中创建一个卡片 -->
    <div class="mdl-card">
      <div class="mdl-card__title">
        <h2 class="mdl-card__title-text">对话框标题</h2>
      </div>
      <div class="mdl-card__supporting-text">
        <!-- 在卡片中插入图像 -->
        <img src="path/to/image.jpg" alt="图像描述">
      </div>
    </div>
  </div>
  <div class="mdl-dialog__actions">
    <button type="button" class="mdl-button close">关闭</button>
  </div>
</dialog>

<!-- 初始化对话框组件 -->
<script>
  var dialog = document.querySelector('dialog');
  var showDialogButton = document.querySelector('#show-dialog');
  if (!dialog.showModal) {
    dialogPolyfill.registerDialog(dialog);
  }
  showDialogButton.addEventListener('click', function() {
    dialog.showModal();
  });
  dialog.querySelector('.close').addEventListener('click', function() {
    dialog.close();
  });
</script>