This reverts commit 380dba0a.

Reason for revert: Fails gc-stress: https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Mac64%20GC%20Stress/1471

Original change's description:
> [runtime][gc] Drop AllocationSite::weak_next field for sub-literals
> 
> Use AllocationSite without Weaknext field for all the allocations in nested
> literal except for Root. The nested field is sufficient to link all the
> allocations in a nested literal. Only the Root is added to heap weak_alloc_list
> for GC to traverse
> 
> Change-Id: I946e63292c6d168197cd2a087f697c73cc431272
> Reviewed-on: https://chromium-review.googlesource.com/1101323
> Commit-Queue: Chandan Reddy <chandanreddy@google.com>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#53813}

TBR=ulan@chromium.org,cbruni@chromium.org,chandanreddy@google.com

Change-Id: Icc87027f14f917da3033db256c2535e08e2a4a34
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/1105159Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53815}