The message on the DCHECK says that no compilation should have started
when adding js-to-wasm units, but the check itself then also allows for
situations where the job was created but is already done. This is
unnecessarily permissive.
This CL fixes the DCHECK to check what the comment says.

R=ahaas@chromium.org

Change-Id: I6de8af33869fd11ae91ce2009c360b8d4ed54e9e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2529142Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71111}