This reverts commit 8be6842c.

Reason for revert: gc stress still broken:
https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20GC%20Stress%20-%20custom%20snapshot/builds/18635
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20gc%20stress/builds/15893

Original change's description:
> Fix GC stress after r52416
> 
> Allocating elements and/or property backing stores can, due to retrying,
> cause a JSObject that has just been allocated in new space to be promoted
> to old space, so skipping the write barrier is now an invalid optimization.
> 
> Tbr: hpayer@chromium.org
> Change-Id: I4a1eacbd59912dd4aa9069b0636f683fb4674231
> Reviewed-on: https://chromium-review.googlesource.com/998799
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#52417}

TBR=jkummerow@chromium.org,hpayer@chromium.org

Change-Id: I2c29f34ea8ae950985c1638c21003e1025db06be
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/999512Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52419}