(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.
startPhaseTimer(finishedWork, 'componentDidUpdate');
          instance.props = finishedWork.memoizedProps;
          instance.state = finishedWork.memoizedState;
          instance.componentDidUpdate(
            prevProps,
            prevState,
            instance.__reactInternalSnapshotBeforeUpdate,
          );
          stopPhaseTimer();
        }
      }
      const updateQueue = finishedWork.updateQueue;
      if (updateQueue !== null) {
        instance.props = finishedWork.memoizedProps;
        instance.state = finishedWork.memoizedState;
        commitUpdateQueue(
          finishedWork,
          updateQueue,
          instance,
          committedExpirationTime,
        );
      }
      return;
    }
    case HostRoot: {
      const updateQueue = finishedWork.updateQueue;
      if (updateQueue !== null) {
        let instance = null;
        if (finishedWork.child !== null) {
          switch (finishedWork.child.tag) {