This reverts commit c87f8954.

Reason for revert: LazyDeoptimizationMultithread failing.

https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20TSAN%20-%20concurrent%20marking/builds/1876/steps/Bisect%20c87f8954.Retry/logs/LazyDeoptimizationMul..

Original change's description:
> Deoptimization and multithreading. 
> 
> When using Lockers and Unlockers it is possible to create a 
> scenario where multiple threads point to the same optimized 
> code object. When that happens, if one of the threads triggers
> deoptimization, then the stack replacement needs to happen in 
> the stacks of all threads.
> With this CL, the deoptimizer visits all threads to do so.
> The CL also adds three tests where V8 used to crash.
> 
> Bug: v8:6563
> Change-Id: Iea88f47af2f31181c0ef06d898faccde9ad14432
> Reviewed-on: https://chromium-review.googlesource.com/657423
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Commit-Queue: Juliana Patricia Vicente Franco <jupvfranco@google.com>
> Cr-Commit-Position: refs/heads/master@{#48033}

TBR=mstarzinger@chromium.org,jarin@chromium.org,bmeurer@chromium.org,jupvfranco@google.com

Change-Id: I290c9e339c367f68c0d1b6f7c0780cdbbbdf3f8a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6563
Reviewed-on: https://chromium-review.googlesource.com/669399Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48049}