Revert of Introduce a separate FunctionLiteral ID for Eval (patchset #1 id:1 of https://codereview.chromium.org/2533303006/ )

Reason for revert:
My assumption that eval and top-level code should be handled differently was wrong

Original issue's description:
> Introduce a separate FunctionLiteral ID for Eval
>
> Top level SharedFunctionInfos will end up in a scripts SFI list, but
> eval'd SFIs shouldn't. Separate IDs will allow for adding a
> corresponding DCHECK.
>
> BUG=v8:5589
> R=marja@chromium.org
>
> Committed: https://crrev.com/c6d421ff9aee7f3cab9e48faac88f6b08d2f1cf5
> Cr-Commit-Position: refs/heads/master@{#41421}

TBR=marja@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5589

Review-Url: https://codereview.chromium.org/2544003003
Cr-Commit-Position: refs/heads/master@{#41448}