Update gc branch to bleeding_edge revision 8862.

src/mark-compact.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 472 matching lines @@
     }
   }
 
   void MigrateObject(Address dst,
                      Address src,
                      int size,
                      AllocationSpace to_old_space);
 
   bool TryPromoteObject(HeapObject* object, int object_size);
 
+  inline Object* encountered_weak_maps() { return encountered_weak_maps_; }
+  inline void set_encountered_weak_maps(Object* weak_map) {
+    encountered_weak_maps_ = weak_map;
+  }
+
  private:
   MarkCompactCollector();
   ~MarkCompactCollector();
 
 #ifdef DEBUG
   enum CollectorState {
     IDLE,
     PREPARE_GC,
     MARK_LIVE_OBJECTS,
     SWEEP_SPACES,
@@ skipping 116 matching lines @@
   // Map transitions from a live map to a dead map must be killed.
   // We replace them with a null descriptor, with the same key.
   void ClearNonLiveTransitions();
 
   // Marking detaches initial maps from SharedFunctionInfo objects
   // to make this reference weak. We need to reattach initial maps
   // back after collection. This is either done during
   // ClearNonLiveTransitions pass or by calling this function.
   void ReattachInitialMaps();
 
+  // Mark all values associated with reachable keys in weak maps encountered
+  // so far.  This might push new object or even new weak maps onto the
+  // marking stack.
+  void ProcessWeakMaps();
+
+  // After all reachable objects have been marked those weak map entries
+  // with an unreachable key are removed from all encountered weak maps.
+  // The linked list of all encountered weak maps is destroyed.
+  void ClearWeakMaps();
+
   // -----------------------------------------------------------------------
   // Phase 2: Sweeping to clear mark bits and free non-live objects for
   // a non-compacting collection.
   //
   //  Before: Live objects are marked and non-live objects are unmarked.
   //
   //   After: Live objects are unmarked, non-live regions have been added to
   //          their space's free list. Active eden semispace is compacted by
   //          evacuation.
   //
@@ skipping 59 matching lines @@
   friend class MarkObjectVisitor;
   static void VisitObject(HeapObject* obj);
 
   friend class UnmarkObjectVisitor;
   static void UnmarkObject(HeapObject* obj);
 #endif
 
   Heap* heap_;
   MarkingDeque marking_deque_;
   CodeFlusher* code_flusher_;
+  Object* encountered_weak_maps_;
 
   List<Page*> evacuation_candidates_;
 
   friend class Heap;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_MARK_COMPACT_H_