[heap] Fix space DCHECK in Scavenger::ScavengeObject to allow young generation LOs.

Bug: chromium:852420
Change-Id: I920c4ac8e66a7f29c28fcc62a0b1ea62370bdf5d
Reviewed-on: https://chromium-review.googlesource.com/c/1350993Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57842}

src/heap/scavenger-inl.h

@@ -372,7 +372,11 @@ SlotCallbackResult Scavenger::ScavengeObject(HeapObjectSlot p,
       DCHECK((*p)->IsStrong());
       p.store(HeapObjectReference::Strong(dest));
     }
-    DCHECK(Heap::InToSpace(dest) || !Heap::InNewSpace((dest)));
+    DCHECK_IMPLIES(Heap::InNewSpace(dest),
+                   (Heap::InToSpace(dest) ||
+                    MemoryChunk::FromHeapObject(dest)->owner()->identity() ==
+                        NEW_LO_SPACE));
+
     return Heap::InToSpace(dest) ? KEEP_SLOT : REMOVE_SLOT;
   }