<!--
  Note: if the issue is about documentation or the website, please file it at:
  https://github.com/reactjs/reactjs.org/issues/new
-->

**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

enableProfilerTimer = true,
  enableSchedulerTracing = true,
  replayFailedUnitOfWorkWithInvokeGuardedCallback = false,
  useNoopRenderer = false,
} = {}) {
  let currentTime = 0;
  mockNow = jest.fn().mockImplementation(() => currentTime);
  global.Date.now = mockNow;
  ReactFeatureFlags = require('shared/ReactFeatureFlags');
  ReactFeatureFlags.debugRenderPhaseSideEffects = false;
  ReactFeatureFlags.debugRenderPhaseSideEffectsForStrictMode = false;
  ReactFeatureFlags.enableProfilerTimer = enableProfilerTimer;
  ReactFeatureFlags.enableSchedulerTracing = enableSchedulerTracing;
  ReactFeatureFlags.replayFailedUnitOfWorkWithInvokeGuardedCallback = replayFailedUnitOfWorkWithInvokeGuardedCallback;
  React = require('react');
  SchedulerTracing = require('scheduler/tracing');
  ReactCache = require('react-cache');
  if (useNoopRenderer) {
    ReactNoop = require('react-noop-renderer');
    ReactTestRenderer = null;
  } else {
    ReactNoop = null;
    ReactTestRenderer = require('react-test-renderer');
    ReactTestRenderer.unstable_setNowImplementation(mockNow);
  }