Nested suspense boundaries

Nested suspense boundaries are also supported and works even if the nested content is ready first.

<Suspense>
  <p slot="fallback">Loading...</p>
  <SimpleExample delay={3000} />

  <Suspense>
    <p slot="fallback">Loading nested 1...</p>
    <SimpleExample delay={5000} />
  </Suspense>

  <Suspense>
    <p slot="fallback">Loading nested 2...</p>
    <SimpleExample delay={2000} />
  </Suspense>
</Suspense>