[es6] conditionally ignore TDZ semantics for formals

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index 4f710fb65a7301543da44fa206300506d9afd255..69005df4954e15a2dceb8ccabd250a45fb2b081b 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -30,6 +30,7 @@ struct FormalParametersBase {
   Scope* scope;
   bool has_rest = false;
   bool is_simple = true;
+  bool contains_expressions = false;
   int materialized_literals_count = 0;
   mutable int rest_array_literal_index = -1;
 };
@@ -1788,7 +1789,8 @@ class PreParser : public ParserBase<PreParserTraits> {
   // the final '}'.
   PreParseResult PreParseLazyFunction(
       LanguageMode language_mode, FunctionKind kind, bool has_simple_parameters,
-      ParserRecorder* log, Scanner::BookmarkScope* bookmark = nullptr);
+      bool has_parameter_expressions, ParserRecorder* log,
+      Scanner::BookmarkScope* bookmark = nullptr);
 
  private:
   friend class PreParserTraits;
@@ -2611,6 +2613,8 @@ ParserBase<Traits>::ParsePropertyDefinition(
     this->PushLiteralName(fni_, name);
   }
 
+  if (*is_computed_name) classifier->RecordContainsExpressions();
+
   if (!in_class && !is_generator && peek() == Token::COLON) {
     // PropertyDefinition : PropertyName ':' AssignmentExpression
     if (!*is_computed_name) {
@@ -2714,6 +2718,7 @@ ParserBase<Traits>::ParsePropertyDefinition(
                              ExpressionClassifier::ExpressionProductions);
       value = factory()->NewAssignment(Token::ASSIGN, lhs, rhs,
                                        RelocInfo::kNoPosition);
+      classifier->RecordContainsExpressions();
     } else {
       value = lhs;
     }
@@ -2904,6 +2909,11 @@ ParserBase<Traits>::ParseAssignmentExpression(bool accept_IN,
     if (!arrow_formals_classifier.is_simple_parameter_list()) {
       scope->SetHasNonSimpleParameters();
       parameters.is_simple = false;
+
+      if (arrow_formals_classifier.contains_expressions()) {
+        parameters.contains_expressions = true;
+        scope->SetHasParameterExpressions();
+      }
     }
 
     Scanner::Location duplicate_loc = Scanner::Location::invalid();
@@ -2948,6 +2958,8 @@ ParserBase<Traits>::ParseAssignmentExpression(bool accept_IN,
     classifier->RecordBindingPatternError(scanner()->location(),
                                           MessageTemplate::kUnexpectedToken,
                                           Token::String(op));
+  } else {
+    classifier->RecordContainsExpressions();
   }
   int pos = position();
 
@@ -3743,6 +3755,7 @@ void ParserBase<Traits>::ParseFormalParameter(
     if (!*ok) return;
     parameters->is_simple = false;
     classifier->RecordNonSimpleParameter();
+    classifier->RecordContainsExpressions();
   }
 
   Traits::AddFormalParameter(parameters, pattern, initializer, is_rest);
@@ -3793,6 +3806,11 @@ void ParserBase<Traits>::ParseFormalParameterList(
     }
   }
 
+  parameters->contains_expressions = classifier->contains_expressions();
+  if (parameters->contains_expressions) {
+    parameters->scope->SetHasParameterExpressions();
+  }
+
   for (int i = 0; i < parameters->Arity(); ++i) {
     auto parameter = parameters->at(i);
     Traits::DeclareFormalParameter(parameters->scope, parameter, classifier);