Use WeakCells in the optimized code map rather than traversing in pause.

src/contexts.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_CONTEXTS_H_
 #define V8_CONTEXTS_H_
 
 #include "src/heap/heap.h"
 #include "src/objects.h"
 
@@ skipping 209 matching lines @@
   V(OBJECT_FUNCTION_INDEX, JSFunction, object_function)                        \
   V(OBJECT_FUNCTION_PROTOTYPE_MAP_INDEX, Map, object_function_prototype_map)   \
   V(OPAQUE_REFERENCE_FUNCTION_INDEX, JSFunction, opaque_reference_function)    \
   V(PROXY_FUNCTION_INDEX, JSFunction, proxy_function)                          \
   V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function)                        \
   V(REGEXP_RESULT_MAP_INDEX, Map, regexp_result_map)                           \
   V(RUNTIME_CONTEXT_INDEX, Context, runtime_context)                           \
   V(SCRIPT_CONTEXT_TABLE_INDEX, ScriptContextTable, script_context_table)      \
   V(SCRIPT_FUNCTION_INDEX, JSFunction, script_function)                        \
   V(SECURITY_TOKEN_INDEX, Object, security_token)                              \
+  V(SELF_WEAK_CELL_INDEX, WeakCell, self_weak_cell)                            \
   V(SET_ITERATOR_MAP_INDEX, Map, set_iterator_map)                             \
   V(SHARED_ARRAY_BUFFER_FUN_INDEX, JSFunction, shared_array_buffer_fun)        \
   V(SLOPPY_ARGUMENTS_MAP_INDEX, Map, sloppy_arguments_map)                     \
   V(SLOPPY_FUNCTION_MAP_INDEX, Map, sloppy_function_map)                       \
   V(SLOPPY_FUNCTION_WITHOUT_PROTOTYPE_MAP_INDEX, Map,                          \
     sloppy_function_without_prototype_map)                                     \
   V(SLOPPY_FUNCTION_WITH_READONLY_PROTOTYPE_MAP_INDEX, Map,                    \
     sloppy_function_with_readonly_prototype_map)                               \
   V(SLOPPY_GENERATOR_FUNCTION_MAP_INDEX, Map, sloppy_generator_function_map)   \
   V(SLOW_ALIASED_ARGUMENTS_MAP_INDEX, Map, slow_aliased_arguments_map)         \
@@ skipping 313 matching lines @@
 #endif
 
   STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);
   STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CONTEXTS_H_