Add strong mode.

src/ast-value-factory.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 241 matching lines @@
   F(let, "let")                                         \
   F(make_reference_error, "MakeReferenceErrorEmbedded") \
   F(make_syntax_error, "MakeSyntaxErrorEmbedded")       \
   F(make_type_error, "MakeTypeErrorEmbedded")           \
   F(native, "native")                                   \
   F(next, "next")                                       \
   F(proto, "__proto__")                                 \
   F(prototype, "prototype")                             \
   F(this, "this")                                       \
   F(use_asm, "use asm")                                 \
+  F(use_strong, "use strong")                           \
   F(use_strict, "use strict")                           \
   F(value, "value")
 
 #define OTHER_CONSTANTS(F) \
   F(true_value)            \
   F(false_value)           \
   F(null_value)            \
   F(undefined_value)       \
   F(the_hole_value)
 
@@ skipping 86 matching lines @@
 
 bool AstRawString::IsArguments(AstValueFactory* ast_value_factory) const {
   return ast_value_factory->arguments_string() == this;
 }
 } }  // namespace v8::internal
 
 #undef STRING_CONSTANTS
 #undef OTHER_CONSTANTS
 
 #endif  // V8_AST_VALUE_FACTORY_H_