Revert of Don't use different function scopes when parsing with temp zones (patchset #11 id:200001 of https://codereview.chromium.org/2368313002/ )

Reason for revert:
Revert due to asm.js slowdown

Original issue's description:
> Don't use different function scopes when parsing with temp zones
>
> Previously we'd have a scope in the main zone, and another in the temp zone. Then we carefully copied back data to the main zone. This CL changes it so that the scope is just fixed up to only contain data from the main zone. That avoids additional copies and additional allocations; while not increasing the care that needs to be taken. This will also make it easier to abort preparsing while parsing using a temp zone.
>
> BUG=
>
> Committed: https://crrev.com/f41e7ebd62b32e861b6aa14ad8bfce3018d03c3c
> Cr-Commit-Position: refs/heads/master@{#39800}

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

Review-Url: https://codereview.chromium.org/2379533003
Cr-Commit-Position: refs/heads/master@{#39821}