This reverts commit 8dd405e3.

Reason for revert: MSAN errors: https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20sim%20-%20MSAN/builds/18598

Original change's description:
> [heap] introduce SpaceWithLinearArea class
> 
> NewSpace and OldSpace have linear allocation areas, but presently the
> implementation doesn't share any code and there are subtle differences.
> This CL introduces a superclass 'SpaceWithLinearArea' that will be used
> to refactor and share code.
> 
> Change-Id: I741e6a6ebb9e75c111287214fd1f555fba62c452
> Reviewed-on: https://chromium-review.googlesource.com/809504
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Ali Ijaz Sheikh <ofrobots@google.com>
> Cr-Commit-Position: refs/heads/master@{#49890}

TBR=ulan@chromium.org,ofrobots@google.com

Change-Id: Ibd325c2965b7b8dea36b34a8c4a3ee06ea24e515
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/810664Reviewed-by: Ali Ijaz Sheikh <ofrobots@google.com>
Commit-Queue: Ali Ijaz Sheikh <ofrobots@google.com>
Cr-Commit-Position: refs/heads/master@{#49892}