ES6: Implement WeakSet

src/mark-compact.h

Index: src/mark-compact.h
diff --git a/src/mark-compact.h b/src/mark-compact.h
index a942600d63041516185a13d2f913ae64b87d7421..4063bde2d30d0f7eafb9c324a7e87194b5d5c2c2 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -695,9 +695,11 @@ 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;
+  inline Object* encountered_weak_collections() {
+    return encountered_weak_collections_;
+  }
+  inline void set_encountered_weak_collections(Object* weak_collection) {
+    encountered_weak_collections_ = weak_collection;
   }
 
   void InvalidateCode(Code* code);
@@ -893,15 +895,15 @@ 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();
+  // Mark all values associated with reachable keys in weak collections
+  // encountered so far.  This might push new object or even new weak maps onto
+  // the marking stack.
+  void ProcessWeakCollections();
 
   // 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();
+  void ClearWeakCollections();
 
   // -----------------------------------------------------------------------
   // Phase 2: Sweeping to clear mark bits and free non-live objects for
@@ -943,7 +945,7 @@ class MarkCompactCollector {
   Heap* heap_;
   MarkingDeque marking_deque_;
   CodeFlusher* code_flusher_;
-  Object* encountered_weak_maps_;
+  Object* encountered_weak_collections_;
 
   List<Page*> evacuation_candidates_;
   List<Code*> invalidated_code_;