* Bugfix: Render phase update leads to dropped work
Render phase updates should not affect the `fiber.expirationTime` field.
We don't have to set anything on the fiber because we're going to
process the render phase update immediately.
We also shouldn't reset the `expirationTime` field in between render
passes because it represents the remaining work left in the update
queues. During the re-render, the updates that were skipped in the
original pass are not processed again.
I think my original motivation for using this field for render phase
updates was so I didn't have to add another module level variable.
* Add repro case for #18486
Co-authored-by: Dan Abramov <dan.abramov@me.com>