![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  
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      hasElementUpdatedSinceLastInspected = true;
    }
    const shouldIncludeInTree = !shouldFilterFiber(nextFiber);
    const isSuspense = nextFiber.tag === SuspenseComponent;
    let shouldResetChildren = false;
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    const prevDidTimeout = isSuspense && prevFiber.memoizedState !== null;
    const nextDidTimeOut = isSuspense && nextFiber.memoizedState !== null;
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    if (prevDidTimeout && nextDidTimeOut) {
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      const nextFiberChild = nextFiber.child;
      const nextFallbackChildSet = nextFiberChild
        ? nextFiberChild.sibling
        : null;
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      const prevFiberChild = prevFiber.child;
      const prevFallbackChildSet = prevFiberChild
        ? prevFiberChild.sibling