Revert of [modules] Properly initialize declared variables. (patchset #5 id:80001 of https://codereview.chromium.org/2375793002/ )

Reason for revert:
Suspect for causing win64 debug problems:
https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20debug/builds/12646

Original issue's description:
> [modules] Properly initialize declared variables.
>
> Before evaluating a module, all variables declared at the top-level
> in _any_ of the modules in the dependency graph must be initialized.
> This is observable because a module A can access a variable imported
> from module B (e.g. a function) at a point when module B's body hasn't
> been evaluated yet.
>
> We achieve this by implementing modules internally as generators with
> two states (not initialized, initialized).
>
> R=adamk@chromium.org
> BUG=v8:1569
>
> Committed: https://crrev.com/f4dfb6fbe1cdd9a0f287a1a9c496e1f69f6f5d20
> Cr-Commit-Position: refs/heads/master@{#39871}

TBR=adamk@chromium.org,mstarzinger@chromium.org,neis@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:1569

Review-Url: https://codereview.chromium.org/2379063002
Cr-Commit-Position: refs/heads/master@{#39873}