[api] Prototype WeakRef implementation

src/heap-symbols.h

 // Copyright 2015 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_HEAP_SYMBOLS_H_
 #define V8_HEAP_SYMBOLS_H_
 
 #define INTERNALIZED_STRING_LIST(V)                                \
   V(anonymous_function_string, "(anonymous function)")             \
   V(anonymous_string, "anonymous")                                 \
@@ skipping 169 matching lines @@
   V(undefined_to_string, "[object Undefined]")                     \
   V(unicode_string, "unicode")                                     \
   V(use_asm_string, "use asm")                                     \
   V(use_strict_string, "use strict")                               \
   V(URIError_string, "URIError")                                   \
   V(valueOf_string, "valueOf")                                     \
   V(values_string, "values")                                       \
   V(value_string, "value")                                         \
   V(WeakMap_string, "WeakMap")                                     \
   V(WeakSet_string, "WeakSet")                                     \
+  V(WeakRef_string, "WeakRef")                                     \
   V(weekday_string, "weekday")                                     \
   V(will_handle_string, "willHandle")                              \
   V(writable_string, "writable")                                   \
   V(year_string, "year")
 
 #define PRIVATE_SYMBOL_LIST(V)              \
   V(array_iteration_kind_symbol)            \
   V(array_iterator_next_symbol)             \
   V(array_iterator_object_symbol)           \
   V(call_site_frame_array_symbol)           \
@@ skipping 43 matching lines @@
 // Well-Known Symbols are "Public" symbols, which have a bit set which causes
 // them to produce an undefined value when a load results in a failed access
 // check. Because this behaviour is not specified properly as of yet, it only
 // applies to a subset of spec-defined Well-Known Symbols.
 #define WELL_KNOWN_SYMBOL_LIST(V)                           \
   V(has_instance_symbol, Symbol.hasInstance)                \
   V(is_concat_spreadable_symbol, Symbol.isConcatSpreadable) \
   V(to_string_tag_symbol, Symbol.toStringTag)
 
 #endif  // V8_HEAP_SYMBOLS_H_