当焦点在纸张输入中时，使用Enter提交iron-form不起作用

<iron-form id="myForm">
  <form>
    <paper-input label="纸张输入" id="input"></paper-input>
    <paper-button @click="${handleSubmit}">提交</paper-button>
  </form>
</iron-form>

<script>
  const form = document.querySelector('#myForm');
  const input = document.querySelector('#input');

  function handleSubmit(e) {
    e.preventDefault();
    form.submit();
  }

  input.addEventListener('keydown', (e) => {
    if (e.key === 'Enter') {
      handleSubmit(e);
    }
  });
</script>

<iron-form id="myForm">
  <form>
    <paper-input label="纸张输入" id="input" key-event-target="form"></paper-input>
  </form>
</iron-form>

<iron-form id="myForm">
  <form>
    <paper-input label="纸张输入" id="input" prevent-submit="false"></paper-input>
  </form>
</iron-form>