Treat weak references in context weakly in write barrier.

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 <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 233 matching lines @@
 
 static inline bool IsGrowStoreMode(KeyedAccessStoreMode store_mode) {
   return store_mode >= STORE_AND_GROW_NO_TRANSITION &&
       store_mode <= STORE_AND_GROW_TRANSITION_HOLEY_DOUBLE_TO_OBJECT;
 }
 
 
 enum IcCheckType { ELEMENT, PROPERTY };
 
 
-// Setter that skips the write barrier if mode is SKIP_WRITE_BARRIER.
-enum WriteBarrierMode { SKIP_WRITE_BARRIER, UPDATE_WRITE_BARRIER };
+// SKIP_WRITE_BARRIER skips the write barrier.
+// UPDATE_WEAK_WRITE_BARRIER skips the marking part of the write barrier and
+// only performs the generational part.
+// UPDATE_WRITE_BARRIER is doing the full barrier, marking and generational.
+enum WriteBarrierMode {
+  SKIP_WRITE_BARRIER,
+  UPDATE_WEAK_WRITE_BARRIER,
+  UPDATE_WRITE_BARRIER
+};
 
 
 // Indicates whether a value can be loaded as a constant.
 enum StoreMode { ALLOW_IN_DESCRIPTOR, FORCE_FIELD };
 
 
 // PropertyNormalizationMode is used to specify whether to keep
 // inobject properties when normalizing properties of a JSObject.
 enum PropertyNormalizationMode {
   CLEAR_INOBJECT_PROPERTIES,
@@ skipping 10902 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_