(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.
rootExpirationTime,
      msUntilTimeout,
    );
    return;
  }
   Ready to commit.
  onComplete(root, rootWorkInProgress, expirationTime);
}
function dispatch(
  sourceFiber: Fiber,
  value: mixed,
  expirationTime: ExpirationTime,
) {
  invariant(
    !isWorking || isCommitting,
    'dispatch: Cannot dispatch during the render phase.',
  );
  let fiber = sourceFiber.return;
  while (fiber !== null) {
    switch (fiber.tag) {
      case ClassComponent:
        const ctor = fiber.type;
        const instance = fiber.stateNode;
        if (
          typeof ctor.getDerivedStateFromCatch === 'function' ||
          (typeof instance.componentDidCatch === 'function' &&
            !isAlreadyFailedLegacyErrorBoundary(instance))
        ) {
          const errorInfo = createCapturedValue(value, sourceFiber);
          const update = createClassErrorUpdate(