Revert of Simplify WeakMap and WeakSet tests slightly. (patchset #1 id:1 of...

Revert of Simplify WeakMap and WeakSet tests slightly. (patchset #1 id:1 of https://codereview.chromium.org/903463002/)

Reason for revert:
Revert this patch as the original CL has to be reverted to due to shared win build failure

http://build.chromium.org/p/client.v8/builders/V8%20Win32%20-%20nosnap%20-%20shared/builds/5030/steps/compile/logs/stdio

Original issue's description:
> Simplify WeakMap and WeakSet tests slightly.
>
> R=rossberg@chromium.org
> TEST=cctest/test-weakmaps,cctest/test-weaksets
>
> Committed: https://crrev.com/a90d7a871da19d33e93c8779186408c8d1615cac
> Cr-Commit-Position: refs/heads/master@{#26428}

TBR=rossberg@chromium.org,mstarzinger@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/899833003

Cr-Commit-Position: refs/heads/master@{#26429}