Disable classes in sloppy mode unless --harmony-sloppy is set

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 233 matching lines @@
   F(dot_generator, ".generator")                        \
   F(dot_generator_object, ".generator_object")          \
   F(dot_iterator, ".iterator")                          \
   F(dot_module, ".module")                              \
   F(dot_result, ".result")                              \
   F(empty, "")                                          \
   F(eval, "eval")                                       \
   F(get_template_callsite, "GetTemplateCallSite")       \
   F(initialize_const_global, "initializeConstGlobal")   \
   F(initialize_var_global, "initializeVarGlobal")       \
+  F(let, "let")                                         \
   F(make_reference_error, "MakeReferenceErrorEmbedded") \
   F(make_syntax_error, "MakeSyntaxErrorEmbedded")       \
   F(make_type_error, "MakeTypeErrorEmbedded")           \
   F(module, "module")                                   \
   F(native, "native")                                   \
   F(next, "next")                                       \
   F(proto, "__proto__")                                 \
   F(prototype, "prototype")                             \
   F(this, "this")                                       \
   F(use_asm, "use asm")                                 \
@@ skipping 96 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_