Revert of Implement flag and source getters on RegExp.prototype. (patchset #3 id:50001 of https://codereview.chromium.org/1419823010/ )

Reason for revert:
[Sheriff] Changes layout tests. Please rebase upstream first. E.g.:
http://build.chromium.org/p/client.v8.fyi/builders/V8-Blink%20Linux%2064/builds/2686

Original issue's description:
> Implement flag and source getters on RegExp.prototype.
>
> R=littledan@chromium.org
> BUG=v8:3715, v8:4528
> LOG=Y
>
> Committed: https://crrev.com/60e8877e161fe6175e19fafce2d6ed1c3999cdb1
> Cr-Commit-Position: refs/heads/master@{#31753}

TBR=littledan@chromium.org,jochen@chromium.org,ulan@chromium.org,yangguo@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:3715, v8:4528

Review URL: https://codereview.chromium.org/1427733005

Cr-Commit-Position: refs/heads/master@{#31758}