![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  
currentRootID,
          [((currentCommitProfilingMetadata: any): CommitProfilingData)],
        );
      }
    }
     W
    flushPendingEvents(root);
    if (traceUpdatesEnabled) {
      hook.emit('traceUpdates', traceUpdatesForNodes);
    }
    currentRootID = -1;
  }
  function findAllCurrentHostFibers(id: number): $ReadOnlyArray<Fiber> {
    const fibers = [];
    const fiber = findCurrentFiberUsingSlowPathById(id);
    if (!fiber) {
      return fibers;
    }
     N
    let node: Fiber = fiber;
    while (true) {
      if (node.tag === HostComponent || node.tag === HostText) {
        fibers.push(node);
      } else if (node.child) {
        node.child.return = node;
        node = node.child;
        continue;
      }
      if (node === fiber) {
        return fibers;