Revert of Introduce a kill-switch for shipping features. (patchset #2 id:20001 of https://codereview.chromium.org/763273002/)

Reason for revert:
Reverted for breaking nosnap: http://chromegw.corp.google.com/i/client.v8/builders/V8%20Linux%20-%20nosnap/builds/1003/steps/Check/logs/Threading3

Original issue's description:
> Introduce a kill-switch for shipping features.
>
> R=rossberg@chromium.org
>
> Committed: https://chromium.googlesource.com/v8/v8/+/d6285620868b15c84eb9affa59f6b4e869f074b8

TBR=rossberg@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/763353002

Cr-Commit-Position: refs/heads/master@{#25574}