Enable --harmony-trailing-commas

src/parsing/parser-base.h

Index: src/parsing/parser-base.h
diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
index d8705a654fd535d95fbe5fdcea017852e9241f40..0a9175e9ce81aa7afe0165f070bdeec5792765ea 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -216,7 +216,6 @@ class ParserBase {
         allow_harmony_do_expressions_(false),
         allow_harmony_function_sent_(false),
         allow_harmony_restrictive_generators_(false),
-        allow_harmony_trailing_commas_(false),
         allow_harmony_class_fields_(false),
         allow_harmony_object_spread_(false) {}
 
@@ -229,7 +228,6 @@ class ParserBase {
   ALLOW_ACCESSORS(harmony_do_expressions);
   ALLOW_ACCESSORS(harmony_function_sent);
   ALLOW_ACCESSORS(harmony_restrictive_generators);
-  ALLOW_ACCESSORS(harmony_trailing_commas);
   ALLOW_ACCESSORS(harmony_class_fields);
   ALLOW_ACCESSORS(harmony_object_spread);
 
@@ -1454,7 +1452,6 @@ class ParserBase {
   bool allow_harmony_do_expressions_;
   bool allow_harmony_function_sent_;
   bool allow_harmony_restrictive_generators_;
-  bool allow_harmony_trailing_commas_;
   bool allow_harmony_class_fields_;
   bool allow_harmony_object_spread_;
 
@@ -1908,8 +1905,7 @@ ParserBase<Impl>::ParseExpressionCoverGrammar(bool accept_IN, bool* ok) {
           scanner()->location(), MessageTemplate::kParamAfterRest);
     }
 
-    if (allow_harmony_trailing_commas() && peek() == Token::RPAREN &&
-        PeekAhead() == Token::ARROW) {
+    if (peek() == Token::RPAREN && PeekAhead() == Token::ARROW) {
       // a trailing comma is allowed at the end of an arrow parameter list
       break;
     }
@@ -2616,7 +2612,7 @@ typename ParserBase<Impl>::ExpressionListT ParserBase<Impl>::ParseArguments(
     done = (peek() != Token::COMMA);
     if (!done) {
       Next();
-      if (allow_harmony_trailing_commas() && peek() == Token::RPAREN) {
+      if (peek() == Token::RPAREN) {
         // allow trailing comma
         done = true;
       }
@@ -3552,7 +3548,7 @@ void ParserBase<Impl>::ParseFormalParameterList(FormalParametersT* parameters,
         break;
       }
       if (!Check(Token::COMMA)) break;
-      if (allow_harmony_trailing_commas() && peek() == Token::RPAREN) {
+      if (peek() == Token::RPAREN) {
         // allow the trailing comma
         break;
       }