We don't need to add stability dependencies on JSObject prototypes when
storing to an element, because we do the map check (and thereby guard
the elements kind) and we also properly deoptimize on holes if the array
protector is not usable.

R=verwaest@chromium.org
BUG=chromium:616709

Review-Url: https://codereview.chromium.org/2198833002
Cr-Commit-Position: refs/heads/master@{#38355}