This reverts commit dda0419e.

Reason for revert: msvc unhappy:
https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20msvc/builds/1434

Original change's description:
> [bigint] Add BigInt64Array, BigUint64Array
> 
> Bug: v8:6791
> Tbr: hpayer@chromium.org
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> Change-Id: I637e9084d2fe4869ad0be2fb996149ab9940f346
> Reviewed-on: https://chromium-review.googlesource.com/914513
> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#51342}

TBR=jkummerow@chromium.org,neis@chromium.org,hpayer@chromium.org

Change-Id: I49237fa323f0d3ea70e744d92d5cbdd4d5c4b39f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6791
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/924663Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51344}