testExitDocument() {
    control.render(sandbox);
    assertTrue('Control must be in the document', control.isInDocument());
    assertEquals(
        'Control must have 5 mouse and 3 key event listeners', 8,
        getListenerCount(control));
    assertEquals(
        'Control\'s key event handler must be attached to its ' +
            'key event target',
        control.getKeyEventTarget(), control.getKeyHandler().element_);
    assertTrue(
        'Control\'s element must support keyboard focus',
        dom.isFocusableTabIndex(control.getKeyEventTarget()));

    control.exitDocument();
    assertFalse(
        'Control must no longer be in the document', control.isInDocument());
    assertEquals(
        'Control must have no event listeners', 0, getListenerCount(control));
    assertNull(
        'Control\'s key event handler must be unattached',
        control.getKeyHandler().element_);
    assertFalse(
        'Control\'s element must no longer support keyboard focus',
        dom.isFocusableTabIndex(control.getKeyEventTarget()));
  }
Tests {@link Control#exitDocument}.
@suppress {visibility} suppression
     added to enable type checking