Use heap iterator in store buffer when page was swept precisely.

src/objects.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_H_
 #define V8_OBJECTS_H_
 
 #include "src/allocation.h"
 #include "src/assert-scope.h"
 #include "src/builtins.h"
@@ skipping 1729 matching lines @@
 
   // Iterates over all pointers contained in the object except the
   // first map pointer.  The object type is given in the first
   // parameter. This function does not access the map pointer in the
   // object, and so is safe to call while the map pointer is modified.
   void IterateBody(InstanceType type, int object_size, ObjectVisitor* v);
 
   // Returns the heap object's size in bytes
   inline int Size();
 
+  // Returns true if this heap object contains only references to other
+  // heap objects.
+  inline bool ContainsPointers();
+
   // Given a heap object's map pointer, returns the heap size in bytes
   // Useful when the map pointer field is used for other purposes.
   // GC internal.
   inline int SizeFromMap(Map* map);
 
   // Returns the field at offset in obj, as a read/write Object* reference.
   // Does no checking, and is safe to use during GC, while maps are invalid.
   // Does not invoke write barrier, so should only be assigned to
   // during marking GC.
   static inline Object** RawField(HeapObject* obj, int offset);
@@ skipping 9445 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_