Remove arguments shadow from scopes, stop rewriting parameters.

arguments/src/variables.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 160 matching lines @@
 
   Variable* local_if_not_shadowed() const {
     ASSERT(mode_ == DYNAMIC_LOCAL && local_if_not_shadowed_ != NULL);
     return local_if_not_shadowed_;
   }
 
   void set_local_if_not_shadowed(Variable* local) {
     local_if_not_shadowed_ = local;
   }
 
-  Expression* rewrite() const { return rewrite_; }
-  void set_rewrite(Expression* expr) { rewrite_ = expr; }
+  Slot* rewrite() const { return rewrite_; }
+  void set_rewrite(Slot* expr) { rewrite_ = expr; }
 
   StaticType* type() { return &type_; }
 
  private:
   Scope* scope_;
   Handle<String> name_;
   Mode mode_;
   Kind kind_;
 
   Variable* local_if_not_shadowed_;
 
   // Static type information
   StaticType type_;
 
   // Code generation.
-  // rewrite_ is usually a Slot or a Property, but may be any expression.
-  Expression* rewrite_;
+  Slot* rewrite_;
 
   // Valid as a LHS? (const and this are not valid LHS, for example)
   bool is_valid_LHS_;
 
   // Usage info.
   bool is_accessed_from_inner_scope_;  // set by variable resolver
   bool is_used_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_VARIABLES_H_