testGetContentForDecoratedControl() {
    sandbox.innerHTML = '<div id="empty"></div>\n' +
        '<div id="text">Hello, world!</div>\n' +
        '<div id="element"><span>Foo</span></div>\n' +
        '<div id="nodelist">Hello, <b>world</b>!</div>\n';

    const empty = new Control(null);
    empty.decorate(dom.getElement('empty'));
    assertNull(
        'Content of control decorating empty DIV must be null',
        empty.getContent());
    empty.dispose();

    const text = new Control(null);
    text.decorate(dom.getElement('text'));
    assertEquals(
        'Content of control decorating DIV with text contents ' +
            'must be as expected',
        'Hello, world!', text.getContent().nodeValue);
    text.dispose();

    const element = new Control(null);
    element.decorate(dom.getElement('element'));
    assertEquals(
        'Content of control decorating DIV with element child ' +
            'must be as expected',
        dom.getElement('element').firstChild, element.getContent());
    element.dispose();

    const nodelist = new Control(null);
    nodelist.decorate(dom.getElement('nodelist'));
    assertSameElements(
        'Content of control decorating DIV with mixed ' +
            'contents must be as expected',
        dom.getElement('nodelist').childNodes, nodelist.getContent());
    nodelist.dispose();
  }
Tests {@link Control#getContent}.
@suppress {checkTypes} suppression added
     to enable type checking