Revert of Implement flag and source getters on RegExp.prototype. (patchset #6 id:110001 of https://codereview.chromium.org/1419823010/ )

Reason for revert:
Breaks Chromium tests and blocks the roll: http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_rel_ng/builds/124490

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}
>
> Committed: https://crrev.com/b5c80a31ad266eb38a0cf2ff756be59c66d34aa5
> Cr-Commit-Position: refs/heads/master@{#31773}
>
> Committed: https://crrev.com/85494e90bb63a3a9e19a1bf862cb6bfcb0162ee9
> Cr-Commit-Position: refs/heads/master@{#31782}

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/1432683002

Cr-Commit-Position: refs/heads/master@{#31801}