[heap] Fix CompactionSpace test and move to unittests

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 7557b825e79190db727b92cbb4a03d060ca0594d..cf8379aa087176867aa044cfcd8875959a500b84 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2733,7 +2733,7 @@ class PauseAllocationObserversScope {
 // -----------------------------------------------------------------------------
 // Compaction space that is used temporarily during compaction.
 
-class CompactionSpace : public PagedSpace {
+class V8_EXPORT_PRIVATE CompactionSpace : public PagedSpace {
  public:
   CompactionSpace(Heap* heap, AllocationSpace id, Executability executable)
       : PagedSpace(heap, id, executable) {}