![Screenshot 2019-12-16 10 51 05](https://user-images.githubusercontent.com/793565/70934095-fd91ed80-1ff1-11ea-93b5-746e816585ec.png)
There's seems to be circumstances where unmounted DOM/Fibers are kept alive by React DevTools. They're kept alive in `primaryFibers`:
https://github.com/facebook/react/blob/34527063083195558f98108cde10b5d6ad0d6865/packages/react-devtools-shared/src/backend/renderer.js#L772

It seems like a WeakSet would be appropriate and would remove the leak. Otherwise we'd need to understand why recordUnmount isn't called.

CC @bvaughn  
We don't patch any methods so there is no cleanup.
  }
  function rootSupportsProfiling(root) {
    if (root.memoizedInteractions != null) {
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      return true;
    } else if (
      root.current != null &&
      root.current.hasOwnProperty('treeBaseDuration')
    ) {
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      return true;
    } else {
      return false;
    }
  }
  function flushInitialOperations() {
    const localPendingOperationsQueue = pendingOperationsQueue;
    pendingOperationsQueue = null;
    if (
      localPendingOperationsQueue !== null &&
      localPendingOperationsQueue.length > 0
    ) {
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      localPendingOperationsQueue.forEach(operations => {
        hook.emit('operations', operations);
      });
    } else {