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.
expect(() => instance.replaceState({})).toThrow();
    expect(() => instance.isMounted()).toThrow();
    if (__DEV__) {
      expect((<any>console.warn).calls.count()).toBe(2);
      expect((<any>console.warn).calls.argsFor(0)[0]).toContain(
        'replaceState(...) is deprecated in plain JavaScript React classes'
      );
      expect((<any>console.warn).calls.argsFor(1)[0]).toContain(
        'isMounted(...) is deprecated in plain JavaScript React classes'
      );
    }
  });
  it('supports this.context passed via getChildContext', function() {
    test(React.createElement(ProvideContext), 'DIV', 'bar-through-context');
  });
  it('supports classic refs', function() {
    var instance = test(React.createElement(ClassicRefs), 'DIV', 'foo');
    expect(instance.refs.inner.getName()).toBe('foo');
  });
  it('supports drilling through to the DOM using findDOMNode', function() {
    var instance = test(
      React.createElement(Inner, {name: 'foo'}),
      'DIV',
      'foo'
    );
    var node = ReactDOM.findDOMNode(instance);
    expect(node).toBe(container.firstChild);
  });
});