Update gc branch to bleeding_edge revision 8862.

src/mark-compact.h

Index: src/mark-compact.h
diff --git a/src/mark-compact.h b/src/mark-compact.h
index f656dd513f34b71b4f3fa917d96cc08c4ff2eda9..24adeca7924248779aa0122f1c429ee3e6be1d72 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -490,6 +490,11 @@ class MarkCompactCollector {
 
   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();
@@ -626,6 +631,16 @@ class MarkCompactCollector {
   // 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.
@@ -705,6 +720,7 @@ class MarkCompactCollector {
   Heap* heap_;
   MarkingDeque marking_deque_;
   CodeFlusher* code_flusher_;
+  Object* encountered_weak_maps_;
 
   List<Page*> evacuation_candidates_;