* Don't show "context" for classes without either contextType or contextTypes
* For classes with contextTypes, change the label to "legacy context" instead

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Originally reported by @gaearon via https://github.com/bvaughn/react-devtools-experimental/issues/368
when we switch from primary to fallback.
  function unmountFiberChildrenRecursively(fiber: Fiber) {
    if (__DEBUG__) {
      debug('unmountFiberChildrenRecursively()', fiber);
    }
     W
    const isTimedOutSuspense =
      fiber.tag === ReactTypeOfWork.SuspenseComponent &&
      fiber.memoizedState !== null;
    let child = fiber.child;
    if (isTimedOutSuspense) {
       I
      const primaryChildFragment = fiber.child;
      const fallbackChildFragment = primaryChildFragment
        ? primaryChildFragment.sibling
        : null;
       S
      child = fallbackChildFragment ? fallbackChildFragment.child : null;
    }
    while (child !== null) {
       R
       W
      if (child.return !== null) {
        unmountFiberChildrenRecursively(child);
        recordUnmount(child, true);
      }
      child = child.sibling;
    }
  }
  function recordProfilingDurations(fiber: Fiber) {