testDecorateInternalForSelectableControl() {
    sandbox.innerHTML = '<div id="foo">Hello, <b>World</b>!</div>';
    const foo = dom.getElement('foo');
    control.setAllowTextSelection(true);
    control.decorate(foo);
    assertEquals(
        'Decorated control\'s element must have expected value', foo,
        control.getElement());
    assertFalse(
        'Element must be selectable',
        style.isUnselectable(control.getElement()));
    assertTrue('Control must be visible', control.isVisible());
  }
Tests {@link Control#decorateInternal} with a control that
allows text selection.