This reverts commit 8a1e927f.

Reason for revert: Seems to break chromium build (https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Linux64%20-%20pointer%20compression/1987)

Original change's description:
> Update MicrotaskQueue ring buffer for pointer compression
> 
> This updates MicrotaskQueue to use pointer-compression style object
> reference.
> 
> Bug: v8:8124
> Change-Id: I7bef92a8760609f3045d2025b145b9a0ec880424
> Reviewed-on: https://chromium-review.googlesource.com/c/1478320
> Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
> Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#59762}

TBR=bmeurer@chromium.org,tzik@chromium.org

Change-Id: Id09e98271e3f301985a4312ecec27b2c292f9644
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:8124
Reviewed-on: https://chromium-review.googlesource.com/c/1480381Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59768}