Revert of [es6] stage sticky regexps and RegExp.prototype.flags. (patchset #3 id:40001 of https://codereview.chromium.org/1412133002/ )

Reason for revert:
[sheriff] breaks nosnap:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20nosnap/builds/4816

Original issue's description:
> [es6] stage sticky regexps and RegExp.prototype.flags.
>
> R=littledan@chromium.org
> BUG=v8:4342
> LOG=Y
>
> Committed: https://crrev.com/722719fe31fe7fd5bb50be6256b3581bb28a8169
> Cr-Commit-Position: refs/heads/master@{#31390}

TBR=littledan@chromium.org,yangguo@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4342

Review URL: https://codereview.chromium.org/1403283004

Cr-Commit-Position: refs/heads/master@{#31398}