This reverts commit 5bddc0e1.

Reason for revert: Possible culprit for https://bugs.chromium.org/p/chromium/issues/detail?id=1029863

Original change's description:
> Implement top-level await for REPL mode
> 
> Design doc: bit.ly/v8-repl-mode
> 
> This CL allows the usage of 'await' without wrapping code in an async
> function when using REPL mode in global evaluate. REPL mode evaluate
> is changed to *always* return a Promise. The resolve value of the
> promise is the completion value of the REPL script.
> 
> The implementation is based on two existing mechanisms:
>   - Similar to async functions, the content of a REPL script is
>     enclosed in a synthetic 'try' block. Any thrown error
>     is used to reject the Promise of the REPL script.
> 
>   - The content of the synthetic 'try' block is also re-written the
>     same way a normal script is. This is, artificial assignments to
>     a ".result" variable are inserted to simulate a completion
>     value. The difference for REPL scripts is, that ".result" is
>     used to resolve the Promise of the REPL script.
> 
>   - ".result" is not returned directly but wrapped in an object
>     literal: "{ .repl_result: .result}". This is done to prevent
>     resolved promises from being chained and resolved prematurely:
> 
>     > Promse.resolve(42);
> 
>     should evaluate to a promise, not 42.
> 
> Bug: chromium:1021921
> Change-Id: I00a5aafd9126ca7c97d09cd8787a3aec2821a67f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1900464
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Commit-Queue: Simon Zünd <szuend@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65273}

TBR=yangguo@chromium.org,leszeks@chromium.org,verwaest@chromium.org,szuend@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:1021921
Change-Id: I9eaea584e2e09f3dffcbbca3d75a3c9bcb0a1adf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1948719Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65333}