Neither Member, nor GarbageCollected objects (and friends) should be
allocated on the stack. Create a special test fixture that allows for
writing idiomatic unit tests that depend on allocation but do not pull
in garbage collection.

Bug: chromium:1056170
Change-Id: I4118201a51658f7247412434a867d35c91299439
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2139583Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67046}