This reverts commit 14165a47.

Reason for revert: Fix is incomplete, will reland soon.

Original change's description:
> [proxy] Fix invalid call to getter in [[Get/Set]]
> 
> Fixes the implementation of step 9 in the Proxy's internal [[Get]]
> method:
> 
> Let targetDesc be ? target.[[GetOwnProperty]](P)
> 
> If P is an accessor, this should not result in a call to the getter.
> Likewise in [[Set]].
> 
> https://tc39.github.io/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-get-p-receiver
> 
> Bug: chromium:776338
> Change-Id: Ic06b7eeac6a1ef9606ddda6fa9d6d58b709702fb
> Reviewed-on: https://chromium-review.googlesource.com/731123
> Reviewed-by: Georg Neis <neis@chromium.org>
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48813}

TBR=neis@chromium.org,jgruber@chromium.org

Change-Id: I92a11791b3c6a73ada1f72fe4193c25e7a054746
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:776338
Reviewed-on: https://chromium-review.googlesource.com/732877Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48815}