This reverts commit 392a1217.

Reason for revert: Several failures on mac64 gc stress: https://ci.chromium.org/p/v8/builders/ci/V8%20Mac64%20GC%20Stress/9747

Original change's description:
> Reland "Reland "[runtime] Remove extension slots from context objects""
> 
> This is a reland of c48096d4
> 
> Original change's description:
> > Reland "[runtime] Remove extension slots from context objects"
> >
> > This is a reland of c07c02e1
> >
> > Original change's description:
> > > [runtime] Remove extension slots from context objects
> > >
> > > Context objects have an extension slot, which contains further
> > > additional data that depends on the type of the context.
> > >
> > > This CL removes the extension slot from contexts that don't need
> > > them, hence reducing memory.
> > >
> > > The following contexts will still have an extension slot: native,
> > > module, await, block and with contexts. See objects/contexts.h for
> > > what the slot is used for.
> > > The following contexts will not have an extension slot anymore (they
> > > were not used before): script, catch and builtin contexts.
> > > Eval and function contexts only have the extension slot if they
> > > contain a sloppy eval.
> > >
> > > Bug: v8:9744
> > > Change-Id: I8ca56c22fa02437bbac392ea72174ebfca80e030
> > > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1863191
> > > Commit-Queue: Victor Gomes <victorgomes@google.com>
> > > Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> > > Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> > > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > > Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> > > Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> > > Auto-Submit: Victor Gomes <victorgomes@google.com>
> > > Cr-Commit-Position: refs/heads/master@{#64372}
> >
> > TBR=verwaest@chromium.org,jgruber@chromium.org,ulan@chromium.org,leszeks@chromium.org,petermarshall@chromium.org
> >
> > Bug: v8:9744
> > Change-Id: I0749cc2d8f59940c25841736634a70047116d647
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1869192
> > Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> > Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> > Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> > Commit-Queue: Peter Marshall <petermarshall@chromium.org>
> > Auto-Submit: Victor Gomes <victorgomes@google.com>
> > Cr-Commit-Position: refs/heads/master@{#64380}
> 
> TBR=verwaest@chromium.org,jgruber@chromium.org,ulan@chromium.org,leszeks@chromium.org,petermarshall@chromium.org
> 
> Bug: v8:9744
> Change-Id: I621ffe98722f8c4defaf277b8d1666484ba2963f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1872400
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> Commit-Queue: Victor Gomes <victorgomes@google.com>
> Cr-Commit-Position: refs/heads/master@{#64451}

TBR=ulan@chromium.org,jgruber@chromium.org,petermarshall@chromium.org,leszeks@chromium.org,verwaest@chromium.org,victorgomes@google.com

Change-Id: I99a71180c6a00a87478867a8210ff9ceb46cb3ee
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9744
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1872405Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64453}