[d8] Fix the shared-library build

src/heap/incremental-marking.h

Index: src/heap/incremental-marking.h
diff --git a/src/heap/incremental-marking.h b/src/heap/incremental-marking.h
index 13753c7b9596550581f004ca2441a3cb1d44b517..51dc97cdc18b3a06184054a79db1cd4a0817f8ab 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -154,8 +154,8 @@ class IncrementalMarking {
   INLINE(void RecordWriteOfCodeEntry(JSFunction* host, Object** slot,
                                      Code* value));
 
-
-  void RecordWriteSlow(HeapObject* obj, Object** slot, Object* value);
+  V8_EXPORT_PRIVATE void RecordWriteSlow(HeapObject* obj, Object** slot,
+                                         Object* value);
   void RecordWriteIntoCodeSlow(Code* host, RelocInfo* rinfo, Object* value);
   void RecordWriteOfCodeEntrySlow(JSFunction* host, Object** slot, Code* value);
   void RecordCodeTargetPatch(Code* host, Address pc, HeapObject* value);