This reverts commit c07c02e1.

Reason for revert: MSAN failures:
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20arm64%20-%20sim%20-%20MSAN/29251

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

Change-Id: I98dee04ab4d3ae977053982ec884b738d2f6f623
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9744
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1868611Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Commit-Queue: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64373}