Remove ARGUMENTS_VARIABLE and fix crankshaft to properly detect the arguments object and keep it al…

src/ast/variables.h

Index: src/ast/variables.h
diff --git a/src/ast/variables.h b/src/ast/variables.h
index a838e2defb476e3357fa90462d87d7af9e06242e..5bc7869646de4d0de37514f1b21602776e519b86 100644
--- a/src/ast/variables.h
+++ b/src/ast/variables.h
@@ -78,7 +78,6 @@ class Variable final : public ZoneObject {
 
   bool is_function() const { return kind() == FUNCTION_VARIABLE; }
   bool is_this() const { return kind() == THIS_VARIABLE; }
-  bool is_arguments() const { return kind() == ARGUMENTS_VARIABLE; }
   bool is_sloppy_function_name() const {
     return kind() == SLOPPY_FUNCTION_NAME_VARIABLE;
   }