Reland of [heap] Fix CompactionSpace test and move to unittests

src/heap/heap.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 728 matching lines @@
   void RepairFreeListsAfterDeserialization();
 
   // Move len elements within a given array from src_index index to dst_index
   // index.
   void MoveElements(FixedArray* array, int dst_index, int src_index, int len);
 
   // Initialize a filler object to keep the ability to iterate over the heap
   // when introducing gaps within pages. If slots could have been recorded in
   // the freed area, then pass ClearRecordedSlots::kYes as the mode. Otherwise,
   // pass ClearRecordedSlots::kNo.
-  HeapObject* CreateFillerObjectAt(Address addr, int size,
-                                   ClearRecordedSlots mode);
+  V8_EXPORT_PRIVATE HeapObject* CreateFillerObjectAt(Address addr, int size,
+                                                     ClearRecordedSlots mode);
 
   bool CanMoveObjectStart(HeapObject* object);
 
   static bool IsImmovable(HeapObject* object);
 
   // Maintain consistency of live bytes during incremental marking.
   void AdjustLiveBytes(HeapObject* object, int by);
 
   // Trim the given array from the left. Note that this relocates the object
   // start and hence is only valid if there is only a single reference to it.
@@ skipping 1858 matching lines @@
   friend class LargeObjectSpace;
   friend class NewSpace;
   friend class PagedSpace;
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_