(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.
lastScheduledRoot = root;
      lastScheduledRoot.nextScheduledRoot = firstScheduledRoot;
    }
  } else {
    
    const remainingExpirationTime = root.expirationTime;
    if (
      remainingExpirationTime === NoWork ||
      expirationTime < remainingExpirationTime
    ) {
      
      root.expirationTime = expirationTime;
    }
  }
}
function findHighestPriorityRoot() {
  let highestPriorityWork = NoWork;
  let highestPriorityRoot = null;
  if (lastScheduledRoot !== null) {
    let previousScheduledRoot = lastScheduledRoot;
    let root = firstScheduledRoot;
    while (root !== null) {
      const remainingExpirationTime = root.expirationTime;
      if (remainingExpirationTime === NoWork) {
        
        
        
        
        invariant(
          previousScheduledRoot !== null && lastScheduledRoot !== null,