The test inspects each builtin's RelocInfo. It's isolate-independent, iff there
are no entries for embedded objects, runtime calls, external references (which
could point to addresses on the isolate), or code targets.

Bug: v8:6666
Change-Id: Ie32353db445a9e81e1c9a0a8f1b5ffe1566a0404
Reviewed-on: https://chromium-review.googlesource.com/888639
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50949}