Reland of Introduce ModulePendingScript (patchset #1 id:1 of https://codereview.chromium.org/2816043005/ )

This CL doesn't change the behavior, because ModulePendingScript is not
used at this time.

Reason for revert:
Issue 711703 is fixed on
https://codereview.chromium.org/2653923008/.

Original issue's description:
> Revert of Introduce ModulePendingScript (patchset #6 id:100001 of https://codereview.chromium.org/2815453006/ )
>
> Reason for revert:
> Reason for revert:
> https://codereview.chromium.org/2653923008/ is
> suspected to cause CHECK() failure (crbug.com/711703)
> inside PendingScript's prefinalizer.
>
> BUG=711703
>
> Original issue's description:
> > Introduce ModulePendingScript
> >
> > BUG=594639
> >
> > Review-Url: https://codereview.chromium.org/2815453006
> > Cr-Commit-Position: refs/heads/master@{#464627}
> > Committed: https://chromium.googlesource.com/chromium/src/+/2e5a5b8efccf655f183cc7ce0c59a88f77bb50f5
>
> TBR=kouhei@chromium.org,yhirano@chromium.org,sigbjornf@opera.com,japhet@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=594639
>
> Review-Url: https://codereview.chromium.org/2816043005
> Cr-Commit-Position: refs/heads/master@{#464765}
> Committed: https://chromium.googlesource.com/chromium/src/+/80f482b929e1a00817069b15e78cc4473eb50c6f

TBR=kouhei@chromium.org,yhirano@chromium.org,sigbjornf@opera.com,japhet@chromium.org
BUG=594639, 711703

Review-Url: https://codereview.chromium.org/2820703003
Cr-Commit-Position: refs/heads/master@{#466909}
3 files changed