Revert of [regexp] Port RegExpCompile and RegExpToString (patchset #3 id:40001 of https://codereview.chromium.org/2295273003/ )

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 RegExpCompile and RegExpToString
>
> BUG=v8:5339
>
> Committed: https://crrev.com/836299aa9c484eb96b6b4aa48270ab2c30b85801
> Cr-Commit-Position: refs/heads/master@{#39119}

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/2311883002
Cr-Commit-Position: refs/heads/master@{#39170}