This reverts commit a9f517e2.

Reason for revert: Makes array sort flaky? https://build.chromium.org/p/client.v8/builders/V8%20Linux64%20-%20debug/builds/17894/steps/OptimizeForSize%20%28flakes%29/logs/array-sort

Original change's description:
> [builtins] Port Proxy set trap to CSA
> 
> Bug: v8:6560, v8:6557
> Change-Id: I329794607e8de324fc696652555aaaeafcf519ec
> Reviewed-on: https://chromium-review.googlesource.com/625940
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Commit-Queue: Maya Lekova <mslekova@google.com>
> Cr-Commit-Position: refs/heads/master@{#47760}

TBR=neis@chromium.org,franzih@chromium.org,ishell@chromium.org,bmeurer@chromium.org,mslekova@google.com

Change-Id: Ibebf5e694945e59bd2808841108e6686af51efaf
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6560, v8:6557
Reviewed-on: https://chromium-review.googlesource.com/646169Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47764}