Reland of https://chromium-review.googlesource.com/c/v8/v8/+/727893
The crashes should be fixed by https://chromium-review.googlesource.com/c/v8/v8/+/763531

Original change's description:
> Revert "Reland^5 "[turbofan] eagerly prune None types and deadness from the graph""
> 
> This reverts commit ac0661b3.
> 
> Reason for revert: Clusterfuzz unhappy: chromium:783019 chromium:783035
> 
> Original change's description:
> > Reland^5 "[turbofan] eagerly prune None types and deadness from the graph"
> >
> > This gives up on earlier attempts to interpret DeadValue as a signal of
> > unreachable code. This does not work because free-floating dead value
> > nodes, and even pure branch nodes that use them, can get scheduled so
> > early that they get reachable. Instead, we now eagerly remove branches
> > that use DeadValue in DeadCodeElimination and replace DeadValue inputs
> > to value phi nodes with dummy values.
> >
> > Reland of https://chromium-review.googlesource.com/715716
> >
> > Bug: chromium:741225 chromium:776256
> > Change-Id: I251efd507c967d4a8882ad8fd2fd96c4185781fe
> > Reviewed-on: https://chromium-review.googlesource.com/727893
> > Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> > Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#49188}
> 
> TBR=jarin@chromium.org,tebbi@chromium.org
> 
> Bug: chromium:741225 chromium:776256 chromium:783019 chromium:783035
> Change-Id: I6a8fa3a08ce2824a858ae01817688e63ed1f442e
> Reviewed-on: https://chromium-review.googlesource.com/758770
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49262}

TBR=jarin@chromium.org,tebbi@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:741225 chromium:776256 chromium:783019 chromium:783035
Change-Id: I6c02b4beb02997ec34015ed2f6791a93c70f5e36
Reviewed-on: https://chromium-review.googlesource.com/772150
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49429}