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.
state = {
    bar: this.props.initialValue
  };
  componentWillMount() {
    this.setState({ bar: 'bar' });
  }
  render() {
    renderCount++;
    return React.createElement('span', {className: this.state.bar});
  }
}
class ArrayState extends React.Component {
  state = ['an array'];
  render() {
    return React.createElement('span');
  }
}
class StringState extends React.Component {
  state = 'a string';
  render() {
    return React.createElement('span');
  }
}
class NumberState extends React.Component {