![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 true;
              }
              prevContext = prevContext.next;
              nextContext = nextContext.next;
            }
            return false;
          }
          break;
        default:
          break;
      }
    }
    return null;
  }
  function areHookInputsEqual(
    nextDeps: Array<mixed>,
    prevDeps: Array<mixed> | null,
  ) {
    if (prevDeps === null) {
      return false;
    }
    for (let i = 0; i < prevDeps.length && i < nextDeps.length; i++) {
      if (is(nextDeps[i], prevDeps[i])) {
        continue;
      }
      return false;
    }
    return true;
  }
  function isEffect(memoizedState) {