Revert of [regexp] Port RegExpConstructor (patchset #2 id:20001 of https://codereview.chromium.org/2302773002/ )

Reason for revert:
Performance regressions: crbug.com/644087
Clusterfuzz: crbug.com/644074

We'll reland all regexp changes at once when the port is complete and at least performance-neutral, since the partial port requires slow workarounds.

Original issue's description:
> [regexp] Port RegExpConstructor
>
> BUG=v8:5339
>
> Committed: https://crrev.com/0aa80be16b8d876999066545c2922e1291e09610
> Cr-Commit-Position: refs/heads/master@{#39074}

TBR=bmeurer@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=v8:5339

Review-Url: https://codereview.chromium.org/2312743002
Cr-Commit-Position: refs/heads/master@{#39177}