Tweak compaction candidate selection to avoid keeping page with low occupancy around.

src/mark-compact-inl.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 28 matching lines @@
 
 MarkBit Marking::MarkBitFrom(Address addr) {
   MemoryChunk* p = MemoryChunk::FromAddress(addr);
   return p->markbits()->MarkBitFromIndex(p->AddressToMarkbitIndex(addr),
                                          p->ContainsOnlyData());
 }
 
 
 void MarkCompactCollector::SetFlags(int flags) {
   sweep_precisely_ = ((flags & Heap::kMakeHeapIterableMask) != 0);
+  reduce_memory_footprint_ = ((flags & Heap::kReduceMemoryFootprintMask) != 0);
 }
 
 
 void MarkCompactCollector::ClearCacheOnMap(Map* map) {
   if (FLAG_cleanup_code_caches_at_gc) {
     map->ClearCodeCache(heap());
   }
 }
 
 
@@ skipping 50 matching lines @@
                             SlotsBuffer::FAIL_ON_OVERFLOW)) {
       EvictEvacuationCandidate(object_page);
     }
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_INL_H_