Revert "Reland "[heap] Attempt to incorporate backing store counters into heap sizing and GC trigger stragery.""

This reverts commit eb164dbd.

Revert "[d8] Fixed external gc test (limit multiplied by number of isolates)."

This reverts commit 38cbc26a.

Revert "[heap] Fixed typo in method name."

This reverts commit 263174af.

Bug: chromium:845409, chromium:879045
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I555bcff2ad04ae23368c7b3999a237083010f9c6
Reviewed-on: https://chromium-review.googlesource.com/1196550Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55529}