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.
return React.createElement('span', {className: this.props.value});
  }
}
var getInitialStateWasCalled = false;
var getDefaultPropsWasCalled = false;
class ClassicProperties extends React.Component {
  contextTypes = {};
  propTypes = {};
  getDefaultProps() {
    getDefaultPropsWasCalled = true;
    return {};
  }
  getInitialState() {
    getInitialStateWasCalled = true;
    return {};
  }
  render() {
    return React.createElement('span', {className: 'foo'});
  }
}
class MisspelledComponent1 extends React.Component {
  componentShouldUpdate() {
    return false;
  }
  render() {
    return React.createElement('span', {className: 'foo'});
  }
}
class MisspelledComponent2 extends React.Component {