Internal references create absolute pointers within the code and must
therefore be disallowed for embedded builtins to remain
position-independent.

Drive-by: remove related cctest. This test used to be relevant before
embedding was fully implemented, but by now it is useless and rather
misleading since it gives a false sense of safety.

Bug: v8:6666
Change-Id: I57a62274b57c3ef1303d5114c68e2a9b1f92bda4
Reviewed-on: https://chromium-review.googlesource.com/1092732
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53623}