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**Do you want to request a *feature* or report a *bug*?**
bug, I believe, unless I misunderstand how it works
**What is the current behavior?**
Given a `Suspense` inside `Suspense` case like
```
<Suspense fallback="Fallback 1">
  <LazyText1 text="First text" />
  <Suspense fallback="Fallback 2">
    <LazyText2 text="Second text!" />
  </Suspense>
</Suspense>
```

Promises in `LazyTexts` start resolving at the same time, but if `LazyText2` is resolved first it never renders, `Fallback 2` stays.

Result:
```
First text

Fallback 2
```

Please see https://codesandbox.io/s/234o4zry7n

**What is the expected behavior?**

Every `LazyText` displayed in the end
```
First text

Second text!
```

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
react, react-dom 16.6.0

expect(didMount).toBe(true);
        expect(callback).toHaveBeenCalledTimes(2);
      });
      it('is not invoked until the commit phase', () => {
        const callback = jest.fn();
        const Yield = ({value}) => {
          ReactTestRenderer.unstable_yield(value);
          return null;
        };
        const renderer = ReactTestRenderer.create(
          <React.unstable_Profiler id="test" onRender={callback}>
            <Yield value="first" />
            <Yield value="last" />
          </React.unstable_Profiler>,
          {
            unstable_isConcurrent: true,
          },
        );
        
        expect(renderer).toFlushAndYieldThrough(['first']);
        expect(callback).toHaveBeenCalledTimes(0);
        expect(renderer).toFlushAndYield(['last']);
        expect(callback).toHaveBeenCalledTimes(1);
      });
      it('does not record times for components outside of Profiler tree', () => {
        ReactTestRenderer.create(
          <div>
            <AdvanceTime />
            <AdvanceTime />
            <AdvanceTime />