This reverts commit da7322c0.

Reason for revert: Breaking the pointer compression bots, e.g.:
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20-%20pointer%20compression/3047

Original change's description:
> [csa] verify skipped write-barriers in MemoryOptimizer
> 
> With very few exceptions, this verifies all skipped write-barriers in
> CSA and Torque, showing that the MemoryOptimizer together with some
> type information on the stored value are enough to avoid unsafe skipped
> write-barriers.
> 
> Changes to CSA:
> SKIP_WRITE_BARRIER and Store*NoWriteBarrier are verified by the
> MemoryOptimizer by default.
> Type information about the stored values (TNode<Smi>) is exploited to
> safely skip write barriers for stored Smi values.
> In some cases, the code is re-structured to make it easier to consume
> for the MemoryOptimizer (manual branch and load elimination).
> 
> Changes to the MemoryOptimizer:
> Improve the MemoryOptimizer to remove write barriers:
> - When the store happens to a CSA-generated InnerAllocate, by ignoring
>   Bitcasts and additions.
> - When the stored value is the HeapConstant of an immortal immovable root.
> - When the stored value is a SmiConstant (recognized by BitcastToTaggedSigned).
> - Fast C-calls are treated as non-allocating.
> - Runtime calls can be white-listed as non-allocating.
> 
> Remaining missing cases:
> - C++-style iterator loops with inner pointers.
> - Inner allocates that are reloaded from a field where they were just stored
>   (for example an elements backing store). Load elimination would fix that.
> - Safe stored value types that cannot be expressed in CSA (e.g., Smi|Hole).
>   We could handle that in Torque.
> - Double-aligned allocations, which are not lowered in the MemoryOptimizer
>   but in CSA.
> 
> Drive-by change: Avoid Smi suffix for StoreFixedArrayElement since this
> can be handled by overload resolution (in Torque and C++).
> 
> R=​jarin@chromium.org
> TBR=mvstanton@chromium.org
> 
> Change-Id: I0af9b710673f350e0fe81c2e59f37da93c024b7c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1571414
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61016}

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

Change-Id: I36877cd6d08761726ef8dce8a3e3f2ce3eebe6cf
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1585732Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61038}