ConcurrentMarkingState and MarkingStateBase are already defined in the

This change fixes compilation with MSVC.

v8: :internal namespace.
Change-Id: Ib8a1370a0a27a90e385fd69e61036e263e1489e6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2562671Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michaël Zasso <mic.besace@gmail.com>
Cr-Commit-Position: refs/heads/master@{#71473}