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.
render() {
          return <div ref={e => refCount++} />;
        }
      }
      await expectMarkupMatch(<RefsComponent />, <div />);
      expect(refCount).toBe(0);
    });
    it('should run ref code on client', async () => {
      let refCount = 0;
      class RefsComponent extends React.Component {
        render() {
          return <div ref={e => refCount++} />;
        }
      }
      await expectMarkupMatch(<div />, <RefsComponent />);
      expect(refCount).toBe(1);
    });
    it('should send the correct element to ref functions on client', async () => {
      let refElement = null;
      class RefsComponent extends React.Component {
        render() {
          return <div ref={e => (refElement = e)} />;
        }
      }
      const e = await clientRenderOnServerString(<RefsComponent />);
      expect(refElement).not.toBe(null);
      expect(refElement).toBe(e);
    });
    it('should have string refs on client when rendered over server markup', async () => {
      class RefsComponent extends React.Component {