(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.
HostEffectMask,
} from 'shared/ReactTypeOfSideEffect';
import {
  HostRoot,
  ClassComponent,
  HostComponent,
  ContextProvider,
  HostPortal,
} from 'shared/ReactTypeOfWork';
import {
  enableProfilerTimer,
  enableUserTimingAPI,
  replayFailedUnitOfWorkWithInvokeGuardedCallback,
  warnAboutDeprecatedLifecycles,
  warnAboutLegacyContextAPI,
  enableSuspense,
} from 'shared/ReactFeatureFlags';
import getComponentName from 'shared/getComponentName';
import invariant from 'shared/invariant';
import warning from 'shared/warning';
import {
  scheduleTimeout,
  cancelTimeout,
  noTimeout,
} from './ReactFiberHostConfig';
import ReactFiberInstrumentation from './ReactFiberInstrumentation';
import ReactDebugCurrentFiber from './ReactDebugCurrentFiber';
import {
  now,
  scheduleDeferredCallback,