[api] Prototype WeakRef implementation

src/heap/objects-visiting.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_VISITING_H_
 #define V8_OBJECTS_VISITING_H_
 
 #include "src/allocation.h"
 #include "src/heap/embedder-tracing.h"
 #include "src/heap/heap.h"
@@ skipping 42 matching lines @@
   V(Oddball)               \
   V(Code)                  \
   V(Map)                   \
   V(Cell)                  \
   V(PropertyCell)          \
   V(WeakCell)              \
   V(TransitionArray)       \
   V(SharedFunctionInfo)    \
   V(JSFunction)            \
   V(JSWeakCollection)      \
+  V(JSWeakRef)             \
   V(JSArrayBuffer)         \
   V(JSRegExp)
 
   // For data objects, JS objects and structs along with generic visitor which
   // can visit object of any size we provide visitors specialized by
   // object size in words.
   // Ids of specialized visitors are declared in a linear order (without
   // holes) starting from the id of visitor specialized for 2 words objects
   // (base visitor id) and ending with the id of generic visitor.
   // Method GetVisitorIdForSize depends on this ordering to calculate visitor
@@ skipping 207 matching lines @@
   INLINE(static void VisitRuntimeEntry(RelocInfo* rinfo)) {}
   // Skip the weak next code link in a code object.
   INLINE(static void VisitNextCodeLink(Heap* heap, Object** slot)) {}
 
  protected:
   INLINE(static void VisitMap(Map* map, HeapObject* object));
   INLINE(static void VisitCode(Map* map, HeapObject* object));
   INLINE(static void VisitBytecodeArray(Map* map, HeapObject* object));
   INLINE(static void VisitSharedFunctionInfo(Map* map, HeapObject* object));
   INLINE(static void VisitWeakCollection(Map* map, HeapObject* object));
+  INLINE(static void VisitWeakRef(Map* map, HeapObject* object));
   INLINE(static void VisitJSFunction(Map* map, HeapObject* object));
   INLINE(static void VisitNativeContext(Map* map, HeapObject* object));
 
   // Mark pointers in a Map treating some elements of the descriptor array weak.
   static void MarkMapContents(Heap* heap, Map* map);
 
   // Code flushing support.
   INLINE(static bool IsFlushable(Heap* heap, JSFunction* function));
   INLINE(static bool IsFlushable(Heap* heap, SharedFunctionInfo* shared_info));
 
@@ skipping 57 matching lines @@
 // the next element. Given the head of the list, this function removes dead
 // elements from the list and if requested records slots for next-element
 // pointers. The template parameter T is a WeakListVisitor that defines how to
 // access the next-element pointers.
 template <class T>
 Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_VISITING_H_