The native context independent (NCI) code variant will be used to test
various aspects as the NCI implementation progresses. Examples:

- Test js-generic-lowering with feedback collection.
- Test NCI codegen without caching or tier-up.
- Test NCI codegen and tier-up without caching.
- Test full NCI (codegen, caching, tier-up).

At some point a build-time flag may be required, we'll see when we get
there.

This variant should be removed once work on NCI is complete.

Bug: v8:8888
Change-Id: I8b12c9a5d69bf167e39e002af385f8f523585550
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2198776
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67767}