[heap] Refactor MC and introduce MarkCompactCollectorBase

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 2637 matching lines @@
   intptr_t step_size_;
   intptr_t bytes_to_next_step_;
 
  private:
   friend class LargeObjectSpace;
   friend class NewSpace;
   friend class PagedSpace;
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
+V8_EXPORT_PRIVATE const char* AllocationSpaceName(AllocationSpace space);
+
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_