(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.
}
  }
  stopCommitSnapshotEffectsTimer();
  if (enableProfilerTimer) {
    
    
    recordCommitTime();
  }
  
  
  
  nextEffect = firstEffect;
  startCommitHostEffectsTimer();
  while (nextEffect !== null) {
    let didError = false;
    let error;
    if (__DEV__) {
      invokeGuardedCallback(null, commitAllHostEffects, null);
      if (hasCaughtError()) {
        didError = true;
        error = clearCaughtError();
      }
    } else {
      try {
        commitAllHostEffects();
      } catch (e) {
        didError = true;
        error = e;
      }
    }