Reland of [heap] Simplify distribution of remaining memory during sweeping & compaction

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index b7aad77a8ec57de202d9f55e57748b9f85a3740d..e233b328511601a46e9a6815763997175cdd9aa1 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2119,17 +2119,12 @@
   // e.g., removes its bump pointer area and resets statistics.
   void MergeCompactionSpace(CompactionSpace* other);
 
-  void DivideUponCompactionSpaces(CompactionSpaceCollection** other, int num,
-                                  intptr_t limit = kCompactionMemoryWanted);
-
   // Refills the free list from the corresponding free list filled by the
   // sweeper.
   virtual void RefillFreeList();
 
  protected:
   void AddMemory(Address start, intptr_t size);
-
-  FreeSpace* TryRemoveMemory(intptr_t size_in_bytes);
 
   void MoveOverFreeMemory(PagedSpace* other);
 
@@ -2893,12 +2888,6 @@
   CompactionSpace(Heap* heap, AllocationSpace id, Executability executable)
       : PagedSpace(heap, id, executable) {}
 
-  // Adds external memory starting at {start} of {size_in_bytes} to the space.
-  void AddExternalMemory(Address start, int size_in_bytes) {
-    IncreaseCapacity(size_in_bytes);
-    Free(start, size_in_bytes);
-  }
-
   bool is_local() override { return true; }
 
   void RefillFreeList() override;