The ForDeopt stub isn't actually necessary anymore; but I don't want to fix the deoptimizer in the same CL.

BUG=v8:5561

Change-Id: I7101cec4b783949bcfbf1ebdb80541d1b558e2e2
Reviewed-on: https://chromium-review.googlesource.com/455858
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43896}