SuspenseList revealOrder="forwards" has issues when Suspense is nested in another element

**Do you want to request a *feature* or report a *bug*?** SuspenseList is currently experimental, so it's neither. But I think that this should be fixed before it's stable. **What is the current behavior?**  Note the 1000ms at the bottom (which should show last based on the `revealOrder`) shows at 2000ms for the nested version. The only difference between those two sets of SuspenseLists is that one has nested the two bottom suspense elements in a `div`. Something like this: ```javascript function App() { return ( <SuspenseList revealOrder="forwards"> <Suspense fallback={<div>2000ms loading</div>}> <A /> </Suspense> <div> {/* nesting */} <Suspense fallback={<div>3000ms loading</div>}> <B /> </Suspense> <Suspense fallback={<div>1000ms loading</div>}> <C /> </Suspense> </div> {/* nesting */} </SuspenseList> ) } ``` https://codesandbox.io/s/suspenselist-issues-sdqzb **What is the expected behavior?** I would expect them to behave exactly the same. Nesting things is often necessary for styling reasons. **Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?** I'm experiencing this on `react@0.0.0-experimental-b53ea6ca0` and `react-dom@0.0.0-experimental-b53ea6ca0`. I don't believe this ever worked in previous versions of React.