(Regarding the experimental `React.unstable_Profiler` API and reactjs/rfcs/pull/51.)

PR #13058 changed the behavior of React profiling builds to opt host roots into `ProfileMode` if the React DevTools extension is detected. This was necessary in order to have accurate tree base time measurements for the visual flame graphs.

The Profiler plug-in for DevTools does feature detection to determine if it's enabled by looking at each root and seeing if any of the fibers contain an `actualDuration` attribute,

The problem is that the `actualDuration` attribute will be present on v16.4 fibers, which pre-date PR #13058. As a result, the Profiler UI may enable itself with versions of React that it cannot work correctly with.

Perhaps an easy solution would be to rename one of the `unstable_Profiler`'s fiber attributes prior to the next minor release (e.g. `treeBaseTime` -> `treeBaseDuration`) and change the DevTools Profiler to feature check using this new name instead.
);
    };
    const onRender = jest.fn(() => {});
    const rendered = ReactTestRenderer.create(<App multiplier={1} />);
    expect(hook.onCommitFiberRoot).toHaveBeenCalledTimes(1);
    
    
    
    expect(onRender).toHaveBeenCalledTimes(1);
    expect(onRender).toHaveBeenCalledWith('Profiler', 'mount', 10, 10, 2, 12);
    onRender.mockClear();
    
    
    
    
    expect(rendered.root.findByType(App)._currentFiber().treeBaseTime).toBe(12);
    rendered.update(<App multiplier={2} />);
    
    
    
    expect(onRender).toHaveBeenCalledTimes(1);
    expect(onRender).toHaveBeenCalledWith('Profiler', 'update', 6, 13, 14, 20);
    
    
    
    
    expect(rendered.root.findByType(App)._currentFiber().treeBaseTime).toBe(15);
  });
  it('should reset the fiber stack correctly after an error when profiling host roots', () => {
    advanceTimeBy(20);