Reason for revert:
Breaks layout tests:
https://build.chromium.org/p/client.v8.fyi/builders/V8-Blink%20Linux%2064/builds/11861

See:
https://github.com/v8/v8/wiki/Blink-layout-tests

Original issue's description:
> Object
> -- New JSObject for promises: JSPromise
>
> Builtins
> -- PromiseThen TFJ
> -- PromiseCreateAndSet TFJ for internal use
> -- PerformPromiseThen TFJ for internal use
> -- PromiseInit for initial promise setup
> -- SpeciesConstructor for use in PromiseThen
> -- ThrowIfNotJSReceiver for use in SpeciesConstructor
> -- AppendPromiseCallback to update FixedArray with new callback
> -- InternalPerformPromiseThen
>
> Promises.js
> -- Cleanup unused symbols
> -- Remove PerformPromiseThen
> -- Remove PromiseThen
> -- Remove PromiseSet
> -- Remove PromiseAttachCallbacks
>
> Runtime
> -- PromiseSet to set promise inobject values
> -- Refactor functions to use FixedArrays for callbacks instead of
>    JSArray
> -- Runtime_PromiseStatus to return promise status
> -- Runtime_PromiseResult to return promise result
> -- Runtime_PromiseDeferred to return deferred attached to promise
> -- Runtime_PromiseRejectReactions to return reject reactions attached
>    to promise
>
> This CL results in a 13.07% improvement in the promises benchmark
> (over 5 runs).
>
> BUG=v8:5343
>
> Committed: https://crrev.com/30b564c76f490f8f6b311a74b25b26cf0a96be2d
> Cr-Commit-Position: refs/heads/master@{#41503}

TBR=bmeurer@chromium.org,jgruber@chromium.org,caitp@igalia.com,gsathya@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5343

Review-Url: https://codereview.chromium.org/2554013002
Cr-Commit-Position: refs/heads/master@{#41512}