This is a reland of 2c0b1f6e

This fixes two bugs:
- Unreachable might have value uses even after being connected
to Throw, so the solution is to just not replace them with the Dead node
anymore.
- We didn't trigger initial visitation of the new Throw node.
  Re-visiting the changed End node takes care of this.


Original change's description:
> [turbofan] re-wire Unreachable to the graph end at EffectPhi's
>
> This avoids the EffectControlLinearizer stumbling upon unreachable
> code.
>
> Bug: chromium:958718
> Change-Id: I135c17813741e48e878a4624370eee1e06081031
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1605737
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61434}

Bug: chromium:958718 chromium:962475 chromium:962474
Change-Id: I388a59912e6260a221cccc76102e0c4b00bff93e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1609791Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61482}