Revert of [es6] Better support for built-ins subclassing. (patchset #8 id:200001 of https://codereview.chromium.org/1427483002/ )

Reason for revert:
Breaks test on win32 nosnap.http://build.chromium.org/p/client.v8/builders/V8%20Win32%20-%20nosnap%20-%20shared/builds/9680

Original issue's description:
> [es6] Better support for built-ins subclassing.
>
> Create proper initial map for original constructor (new.target) instead of doing prototype transition on the base constructor's initial map. This approach fixes in-object slack tracking for subclass instances.
> This CL also fixes subclassing from String.
>
> BUG=v8:3101, v8:3330
> LOG=Y
>
> Committed: https://crrev.com/cd5f48302a502154a0106d12e3066bd563c6340c
> Cr-Commit-Position: refs/heads/master@{#31680}

TBR=verwaest@chromium.org,ulan@chromium.org,ishell@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:3101, v8:3330

Review URL: https://codereview.chromium.org/1416943005

Cr-Commit-Position: refs/heads/master@{#31684}