The new deopt stress is implemented for x64 only.

NOTRY=true
TBR=sergiyb@chromium.org

Bug: v8:6900
Change-Id: I542cb89de643c477875893f6b0b73ced44108b9e
Reviewed-on: https://chromium-review.googlesource.com/708259
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48414}