[es6]: Lexical arguments for arrow functions

src/scopes.h

Index: src/scopes.h
diff --git a/src/scopes.h b/src/scopes.h
index cce8c3c9eaa057558ac38bc953fe9b328719f40f..98bd0ca8987b104df8611266389b248ad2670114 100644
--- a/src/scopes.h
+++ b/src/scopes.h
@@ -394,7 +394,9 @@ class Scope: public ZoneObject {
   }
 
   // The local variable 'arguments' if we need to allocate it; NULL otherwise.
-  Variable* arguments() const { return arguments_; }
+  Variable* arguments() const {
+    return is_arrow_scope() ? nullptr : arguments_;

[adamk, 2015/04/09 15:56:03]

Why is this necessary? Reading the code again, I don't see why arguments_ would
ever get set on arrow scopes. That is, why is arguments ever getting declared as
a local in an arrow scope?

[adamk, 2015/04/09 16:18:04]

Sorry, I've been spending too much time in strict code and keep forgetting how
other bits of scope resolution work. This is fine.

[arv (Not doing code reviews), 2015/04/09 16:53:07]

Changing this to a DCHECK instead.

+  }
 
   // Declarations list.
   ZoneList<Declaration*>* declarations() { return &decls_; }