Removed the invalid DCHECKs altogether.

BUG=v8:5561

Change-Id: I678b80a2f216a84333e3fe65843ca9dfc0bdf0d5
Reviewed-on: https://chromium-review.googlesource.com/458280
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44072}