This CL fixes an issue where getters/setters would get called on a
prototype with the wrong receiver. This happens in the pre-processing
for Array.p.sort when values get copied down from the prototype chain.

R=jgruber@chromium.org

Bug: v8:7682
Change-Id: I0d8ff1dc721c33bd721aaca54ffd357b3d2a2096
Reviewed-on: https://chromium-review.googlesource.com/1198767Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Simon Zünd <szuend@google.com>
Cr-Commit-Position: refs/heads/master@{#55546}