[heap] Fix address space leak in Unmapper

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 0cc162e2cbc18857a00a834136c303c0a755849f..37f1e5cec114df144e2164925758ee5d45f20d46 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -22,7 +22,7 @@ class PagedSpace;
 
 enum class StepOrigin { kV8, kTask };
 
-class IncrementalMarking {
+class V8_EXPORT_PRIVATE IncrementalMarking {
  public:
   enum State { STOPPED, SWEEPING, MARKING, COMPLETE };
 
@@ -151,8 +151,7 @@ class IncrementalMarking {
   INLINE(void RecordWriteOfCodeEntry(JSFunction* host, Object** slot,
                                      Code* value));
 
-  V8_EXPORT_PRIVATE void RecordWriteSlow(HeapObject* obj, Object** slot,
-                                         Object* value);
+  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);