(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.
nextUnitOfWork = createWorkInProgress(
      nextRoot.current,
      null,
      nextRenderExpirationTime,
    );
    root.pendingCommitExpirationTime = NoWork;
  }
  let didFatal = false;
  startWorkLoopTimer(nextUnitOfWork);
  do {
    try {
      workLoop(isYieldy);
    } catch (thrownValue) {
      if (enableProfilerTimer) {
        
        stopBaseRenderTimerIfRunning();
      }
      if (nextUnitOfWork === null) {
        
        didFatal = true;
        onUncaughtError(thrownValue);
      } else {
        if (__DEV__) {
          
          
          (resetCurrentlyProcessingQueue: any)();
        }
        const failedUnitOfWork: Fiber = nextUnitOfWork;
        if (__DEV__ && replayFailedUnitOfWorkWithInvokeGuardedCallback) {
          replayUnitOfWork(failedUnitOfWork, thrownValue, isYieldy);