Revert of Eagerly declare eval scopes, even for sloppy scopes (patchset #2 id:20001 of https://codereview.chromium.org/1085263003/)

Reason for revert:
Regresses CodeLoad (crbug.com/480774).

Original issue's description:
> Eagerly declare eval scopes, even for sloppy scopes
>
> R=marja@chromium.org, mstarzinger@chromium.org
> LOG=N
> BUG=N
>
> Committed: https://crrev.com/fe9efc121c8cba8b6aee1a9cf36c68ee97c44d99
> Cr-Commit-Position: refs/heads/master@{#28027}

TBR=mstarzinger@chromium.org,verwaest@chromium.org,wingo@igalia.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=N

Review URL: https://codereview.chromium.org/1082013003

Cr-Commit-Position: refs/heads/master@{#28037}