Follow up from https://github.com/facebook/react/pull/11616.

Here's one I found. These two invariants:

https://github.com/facebook/react/blob/7e7127387ba64f57299eaff8656542cea6fb3a2d/packages/react-reconciler/src/ReactFiberClassComponent.js#L330-L343

are in a function that's behind a DEV block:

https://github.com/facebook/react/blob/7e7127387ba64f57299eaff8656542cea6fb3a2d/packages/react-reconciler/src/ReactFiberClassComponent.js#L447-L449

I don't think this is intentional, but need to verify.

There may be more. I'll use this issue to track while https://github.com/facebook/react/pull/11616 preserves existing behavior.
'did-mount'
    ]);
    lifeCycles = []; 
    test(React.createElement(NormalLifeCycles, {value: 'bar'}), 'SPAN', 'bar');
    expect(lifeCycles).toEqual([
      'receive-props', { value: 'bar' },
      'should-update', { value: 'bar' }, {},
      'will-update', { value: 'bar' }, {},
      'did-update', { value: 'foo' }, {}
    ]);
    lifeCycles = []; 
    ReactDOM.unmountComponentAtNode(container);
    expect(lifeCycles).toEqual([
      'will-unmount'
    ]);
  });
  it('warns when classic properties are defined on the instance, ' +
     'but does not invoke them.', function() {
    spyOnDev(console, 'error');
    getInitialStateWasCalled = false;
    getDefaultPropsWasCalled = false;
    test(React.createElement(ClassicProperties), 'SPAN', 'foo');
    expect(getInitialStateWasCalled).toBe(false);
    expect(getDefaultPropsWasCalled).toBe(false);
    if (__DEV__) {
      expect((<any>console.error).calls.count()).toBe(4);
      expect((<any>console.error).calls.argsFor(0)[0]).toContain(
        'getInitialState was defined on ClassicProperties, ' +
        'a plain JavaScript class.'
      );