![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  
}
      while (!node.sibling) {
        if (!node.return || node.return === fiber) {
          return fibers;
        }
        node = node.return;
      }
      node.sibling.return = node.return;
      node = node.sibling;
    }
     F
     e
    return fibers;
  }
  function findNativeNodesForFiberID(id: number) {
    try {
      let fiber = findCurrentFiberUsingSlowPathById(id);
      if (fiber === null) {
        return null;
      }
       S
      const isTimedOutSuspense =
        fiber.tag === SuspenseComponent && fiber.memoizedState !== null;
      if (isTimedOutSuspense) {
         A 
         T
        const maybeFallbackFiber = fiber.child && fiber.child.sibling;
        if (maybeFallbackFiber != null) {
          fiber = maybeFallbackFiber;
        }