[strong] Remove all remainders of strong mode

src/ast/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 253 matching lines @@
   F(proto, "__proto__")                         \
   F(prototype, "prototype")                     \
   F(rest_parameter, ".rest_parameter")          \
   F(return, "return")                           \
   F(set_space, "set ")                          \
   F(this, "this")                               \
   F(this_function, ".this_function")            \
   F(throw, "throw")                             \
   F(undefined, "undefined")                     \
   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 84 matching lines @@
   OTHER_CONSTANTS(F)
 #undef F
 };
 }  // namespace internal
 }  // namespace v8
 
 #undef STRING_CONSTANTS
 #undef OTHER_CONSTANTS
 
 #endif  // V8_AST_AST_VALUE_FACTORY_H_