When creating an Element with a ref from inside of a constructor an error is thrown in production mode, but not in dev mode.

Here is a minimal sample:
https://jsfiddle.net/84v837e9/35/

An error, "Only a ReactOwner can have refs", should happen in dev and production modes.

This is happening in React 15.4
render() {
        return <div />;
      }
    }
    var instance = ReactTestUtils.renderIntoDocument(<Component />);
    expect(!!instance.refs).toBe(true);
  });
  function testRefCall() {
    var refCalled = 0;
    function Inner(props) {
      return <a ref={props.saveA} />;
    }
    class Outer extends React.Component {