* setCurrentFiber per fiber, instead of per effect
* Re-use safelyCallDestroy
Part of the code in flushPassiveUnmountEffects is a duplicate of the
code used for unmounting layout effects. I did some minor refactoring to
so we could use the same function in both places.
Closure will inline anyway so it doesn't affect code size or
performance, just maintainability.
* Don't check HookHasEffect during deletion
We don't need to check HookHasEffect during a deletion; all effects are
unmounted.
So we also don't have to set HookHasEffect during a deletion, either.
This allows us to remove the last remaining passive effect logic from
the synchronous layout phase.