[es6] conditionally ignore TDZ semantics for formals

src/scopes.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_SCOPES_H_
 #define V8_SCOPES_H_
 
 #include "src/ast.h"
 #include "src/pending-compilation-error-handler.h"
 #include "src/zone.h"
@@ skipping 385 matching lines @@
   }
 
   bool has_rest_parameter() const {
     return rest_index_ >= 0;
   }
 
   bool has_simple_parameters() const {
     return has_simple_parameters_;
   }
 
+  bool has_parameter_expressions() const { return has_parameter_expressions_; }
+
   // TODO(caitp): manage this state in a better way. PreParser must be able to
   // communicate that the scope is non-simple, without allocating any parameters
   // as the Parser does. This is necessary to ensure that TC39's proposed early
   // error can be reported consistently regardless of whether lazily parsed or
   // not.
   void SetHasNonSimpleParameters() {
     DCHECK(is_function_scope());
     has_simple_parameters_ = false;
   }
 
   // Retrieve `IsSimpleParameterList` of current or outer function.
   bool HasSimpleParameters() {
     Scope* scope = ClosureScope();
     return !scope->is_function_scope() || scope->has_simple_parameters();
   }
 
+  void SetHasParameterExpressions() {
+    DCHECK(is_function_scope());
+    has_parameter_expressions_ = true;
+  }
+
+  bool HasParameterExpressions() {
+    Scope* scope = ClosureScope();
+    return !scope->is_function_scope() || scope->has_parameter_expressions();
+  }
+
   // The local variable 'arguments' if we need to allocate it; NULL otherwise.
   Variable* arguments() const {
     DCHECK(!is_arrow_scope() || arguments_ == nullptr);
     return arguments_;
   }
 
   Variable* this_function_var() const {
     // This is only used in derived constructors atm.
     DCHECK(this_function_ == nullptr ||
            (is_function_scope() && (IsConstructor(function_kind()) ||
@@ skipping 222 matching lines @@
 
   // The number of modules (including nested ones).
   int num_modules_;
 
   // For module scopes, the host scope's temporary variable binding this module.
   Variable* module_var_;
 
   // Info about the parameter list of a function.
   int arity_;
   bool has_simple_parameters_;
+  bool has_parameter_expressions_;
   Variable* rest_parameter_;
   int rest_index_;
 
   // Serialized scope info support.
   Handle<ScopeInfo> scope_info_;
   bool already_resolved() { return already_resolved_; }
 
   // Create a non-local variable with a given name.
   // These variables are looked up dynamically at runtime.
   Variable* NonLocal(const AstRawString* name, VariableMode mode);
@@ skipping 119 matching lines @@
   PendingCompilationErrorHandler pending_error_handler_;
 
   // For tracking which classes are declared consecutively. Needed for strong
   // mode.
   int class_declaration_group_start_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_SCOPES_H_