(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.
}
  }
  isRendering = false;
}
function completeRoot(
  root: FiberRoot,
  finishedWork: Fiber,
  expirationTime: ExpirationTime,
): void {
  
  const firstBatch = root.firstBatch;
  if (firstBatch !== null && firstBatch._expirationTime <= expirationTime) {
    if (completedBatches === null) {
      completedBatches = [firstBatch];
    } else {
      completedBatches.push(firstBatch);
    }
    if (firstBatch._defer) {
      
      
      root.finishedWork = finishedWork;
      root.expirationTime = NoWork;
      return;
    }
  }
  
  root.finishedWork = null;
  commitRoot(root, finishedWork);
}
function shouldYield() {