[es6] support rest parameters in arrow functions (alternative)

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index b57a545ffe0c6940f3d1fcc6dc6bfc71221081e9..6d006957c884d6d204444099b34009507d429f42 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -3611,6 +3611,10 @@ bool CheckAndDeclareArrowParameter(ParserTraits* traits, Expression* expression,
   // Case for a single parameter:
   //   (foo) => ...
   //   foo => ...
+  bool is_rest;
+  if ((is_rest = expression->IsSpread())) {
+    expression = expression->AsSpread()->expression();
+  }
   if (expression->IsVariableProxy()) {
     if (expression->AsVariableProxy()->is_this()) return false;
 
@@ -3625,7 +3629,7 @@ bool CheckAndDeclareArrowParameter(ParserTraits* traits, Expression* expression,
       return false;
     }
 
-    scope->DeclareParameter(raw_name, VAR);
+    scope->DeclareParameter(raw_name, VAR, is_rest);
     ++(*num_params);
     return true;
   }
@@ -4178,8 +4182,9 @@ ClassLiteral* Parser::ParseClassLiteral(const AstRawString* name,
 
   Expression* extends = NULL;
   if (Check(Token::EXTENDS)) {
+    const bool maybeArrow = false;
     block_scope->set_start_position(scanner()->location().end_pos);
-    extends = ParseLeftHandSideExpression(CHECK_OK);
+    extends = ParseLeftHandSideExpression(maybeArrow, CHECK_OK);
   } else {
     block_scope->set_start_position(scanner()->location().end_pos);
   }