Use Scope::function_kind_ to distinguish arrow function scopes

src/preparser.cc

Index: src/preparser.cc
diff --git a/src/preparser.cc b/src/preparser.cc
index 4cea6364a6a369bb6306ec95ee707d8fd9b05843..ecf4a950c0ea8e76192e205020de4713bafb5f40 100644
--- a/src/preparser.cc
+++ b/src/preparser.cc
@@ -111,8 +111,7 @@ PreParser::PreParseResult PreParser::PreParseLazyFunction(
   FunctionState top_state(&function_state_, &scope_, top_scope, kNormalFunction,
                           &top_factory);
   scope_->SetLanguageMode(language_mode);
-  Scope* function_scope = NewScope(
-      scope_, IsArrowFunction(kind) ? ARROW_SCOPE : FUNCTION_SCOPE, kind);
+  Scope* function_scope = NewScope(scope_, FUNCTION_SCOPE, kind);
   if (!has_simple_parameters) function_scope->SetHasNonSimpleParameters();
   PreParserFactory function_factory(NULL);
   FunctionState function_state(&function_state_, &scope_, function_scope, kind,