This reverts commit 591d1c9d.

Reason for revert: breaks blink

Original change's description:
> [top-level-await] Implement top-level-await in V8
> 
> Implements AsyncModules in SourceTextModule. However, there is no
> support in the parser or D8 for actually creating / resolving
> AsyncModules. Also adds a flag '--top-level-await,' but the only
> external facing change with the flag enabled is that Module::Evaluate
> returns a promise.
> 
> Bug: v8:9344
> Change-Id: Idc722efc1e2aa780d04bdb985bb7920ab969d34e
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1728037
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Georg Neis <neis@chromium.org>
> Commit-Queue: Joshua Litt <joshualitt@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#63686}

TBR=ulan@chromium.org,adamk@chromium.org,neis@chromium.org,joshualitt@chromium.org

Change-Id: I6ceeb3a293a948af04bf200ab784ceb03386a3fd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9344
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1797656Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63692}