Revert of [d8] Fix the shared-library build

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index dea49589212f711718676baa65144cb08542a8a8..17180164d47fd3d1ff648c079b6ae4f3b9b77063 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -2417,7 +2417,7 @@
 
 // Space iterator for iterating over all old spaces of the heap: Old space
 // and code space.  Returns each space in turn, and null when it is done.
-class V8_EXPORT_PRIVATE OldSpaces BASE_EMBEDDED {
+class OldSpaces BASE_EMBEDDED {
  public:
   explicit OldSpaces(Heap* heap) : heap_(heap), counter_(OLD_SPACE) {}
   OldSpace* next();