![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  
return getFiberIDUnsafe(parent);
      }
      parent = parent.return;
    }
    return null;
  }
  function inspectElementRaw(id: number): InspectedElement | null {
    const fiber = findCurrentFiberUsingSlowPathById(id);
    if (fiber == null) {
      return null;
    }
    const {
      _debugOwner,
      _debugSource,
      stateNode,
      key,
      memoizedProps,
      memoizedState,
      dependencies,
      tag,
      type,
    } = fiber;
    const elementType = getElementTypeForFiber(fiber);
    const usesHooks =
      (tag === FunctionComponent ||
        tag === SimpleMemoComponent ||