cppgc: Fix atomic read in DCHECK

Pass along the intended atomicity parameter for a getter in a DCHECK.

Bug: chromium:1218072
Change-Id: Ib83c8f548d3de9c944546c74291cd148643e185c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2950242
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75060}

src/heap/cppgc/heap-page.h

@@ -284,7 +284,7 @@ const HeapObjectHeader& BasePage::ObjectHeaderFromInnerAddress(
   SynchronizedLoad();
   const HeapObjectHeader* header =
       ObjectHeaderFromInnerAddressImpl<mode>(this, address);
-  DCHECK_NE(kFreeListGCInfoIndex, header->GetGCInfoIndex());
+  DCHECK_NE(kFreeListGCInfoIndex, header->GetGCInfoIndex<mode>());
   return *header;
 }