![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  
};
        break;
      case ForwardRef:
        global.$r = {
          hooks,
          props,
          type: type.render,
        };
        break;
      case MemoComponent:
      case SimpleMemoComponent:
        global.$r = {
          hooks,
          props,
          type:
            elementType != null && elementType.type != null
              ? elementType.type
              : type,
        };
        break;
      default:
        global.$r = null;
        break;
    }
  }
  function storeAsGlobal(
    id: number,
    path: Array<string | number>,
    count: number,
  ): void {