testIsContainer() {
    const tableNode = $dom(TagName.TABLE);
    const liNode = $dom(TagName.LI);
    const textNode = $text('I am text');
    document.body.appendChild(textNode);

    assertTrue('Table is a container', style.isContainer(tableNode));
    assertTrue('Body is a container', style.isContainer(document.body));
    assertTrue('List item is a container', style.isContainer(liNode));
    assertFalse('Text node is not a container', style.isContainer(textNode));
  }
Test that isContainer returns true when the node is of non-inline HTML and
false when it is not