We should be warning if a controlled component becomes uncontrolled, or vice versa.

I thought this was fixed in https://github.com/facebook/react/issues/5821, but apparently it was either not fixed for checkbox components, or maybe I subsequently broke it in https://github.com/facebook/react/pull/7003 (or similar).  Regardless, we should fix it.

Demo of case that should warn: https://jsfiddle.net/s4742gkk/

<input type="checkbox" checked="false" readOnly={true} />
    );
    expect(console.error.calls.count()).toBe(0);
    ReactTestUtils.renderIntoDocument(
      <input type="checkbox" checked="false" readOnly={false} />
    );
    expect(console.error.calls.count()).toBe(1);
  });
  it('should throw if both checked and checkedLink are provided', function() {
    var node = document.createElement('div');
    var link = new ReactLink(true, jest.fn());
    var instance = <input type="checkbox" checkedLink={link} />;
    expect(() => ReactDOM.render(instance, node)).not.toThrow();
    instance =
      <input
        type="checkbox"
        checkedLink={link}
        checked="false"
        onChange={emptyFunction}
      />;
    expect(() => ReactDOM.render(instance, node)).toThrow();
    instance =
      <input type="checkbox" checkedLink={link} onChange={emptyFunction} />;
    expect(() => ReactDOM.render(instance, node)).toThrow();
  });
  it('should update defaultValue to empty string', function() {
    var container = document.createElement('div');
    ReactDOM.render(<input type="text" defaultValue={'foo'} />, container);
    ReactDOM.render(<input type="text" defaultValue={''} />, container);
    expect(container.firstChild.defaultValue).toBe('');