document:
  nodes:
    - object: block
      type: paragraph
      nodes:
        - object: text
          leaves:
            - text: ''
        - object: inline
          type: html
          isVoid: true
          data:
            openingTag: '<iframe src="src" frameborder="0" width="960" height="569" allowfullscreen mozallowfullscreen webkitallowfullscreen>'
            innerHtml: ''
            closingTag: '</iframe>'
          nodes:
            - object: text
              leaves:
                - text: ' '
        - object: text
          leaves:
            - text: ''