Remove DCHECK because the interpreter may still have activations when
the isolate is torn down. This can happen in particular, when {quit} is
called in d8. A test for this will follow when v8:9209 is resolved.

Change-Id: Ia3ab0daa061d6427df3f778ba5fb195218910280
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1594560
Commit-Queue: Frederik Gossen <frgossen@google.com>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61232}