This CL disables a DCHECK in RemoveArrayHoles that was triggered for
JSArrays that have read-only elements in the prototype chain.

The DCHECK is not removed because it will be re-enabled later when
the copying from the prototype chain (during sorting) will be done
for JSArrays as well.

R=cbruni@chromium.org

Bug: chromium:840855
Change-Id: Ia278bd2f060df094f477b4efbc3f5bdafd7ea7a8
Reviewed-on: https://chromium-review.googlesource.com/1057588Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Simon Zünd <szuend@google.com>
Cr-Commit-Position: refs/heads/master@{#53159}