Revert of [heap] Avoid the use of cells to point from code to new-space objects. (patchset #7 id:120001 of https://codereview.chromium.org/2045263002/ )

Reason for revert:
[Sheriff] Breaks arm debug:
https://build.chromium.org/p/client.v8.ports/builders/V8%20Linux%20-%20arm%20-%20sim%20-%20debug/builds/1038

Original issue's description:
> [heap] Avoid the use of cells to point from code to new-space objects.
>
> Cells were needed originally because there was no typed remembered set to
> record direct pointers from code space to new space. A previous
> CL (https://codereview.chromium.org/2003553002/) already introduced
> the remembered set, this CL uses it.
>
> This CL
> * stores direct pointers in code objects, even if the target is in new space,
> * records the slot of the pointer in typed-old-to-new remembered set,
> * adds a list which stores weak code-to-new-space references,
> * adds a test to test-heap.cc for weak code-to-new-space references,
> * removes prints in tail-call-megatest.js
>
> R=ulan@chromium.org
>
> Committed: https://crrev.com/2d2087b79a293a92a6ed34a2775e481ff2173b3c
> Cr-Commit-Position: refs/heads/master@{#37134}

TBR=titzer@chromium.org,ulan@chromium.org,ahaas@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2087463004
Cr-Commit-Position: refs/heads/master@{#37139}