cppgc: Allow finalizing incremental GC when unsupported

Starting an incremental GC when it is not supported is not allowed but
trying to finalize one when it might be unknown whether it's supported
or not should be legal.
In such cases, finalization would immediately bail out since there is no
active gc.

Bug: chromium:1272076
Change-Id: If5aaaa130dc55474d3fc3afcd7039880a2c11333
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3293411
Auto-Submit: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78010}

src/heap/cppgc/heap.cc

@@ -132,7 +132,6 @@ void Heap::StartIncrementalGarbageCollection(Config config) {
 }
 
 void Heap::FinalizeIncrementalGarbageCollectionIfRunning(Config config) {
-  DCHECK_NE(marking_support_, MarkingType::kAtomic);
   CheckConfig(config, marking_support_, sweeping_support_);
 
   if (!IsMarking()) return;