Clean up some messiness in Scopes.

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 104 matching lines @@
   Variable(Scope* scope,
            Handle<String> name,
            Mode mode,
            bool is_valid_lhs,
            Kind kind);
 
   // Printing support
   static const char* Mode2String(Mode mode);
 
   // Type testing & conversion
-  Property* AsProperty();
-  Variable* AsVariable();
+  Property* AsProperty() const;
+  Slot* AsSlot() const;
+
   bool IsValidLeftHandSide() { return is_valid_LHS_; }
 
   // The source code for an eval() call may refer to a variable that is
   // in an outer scope about which we don't know anything (it may not
   // be the global scope). scope() is NULL in that case. Currently the
   // scope is only used to follow the context chain length.
   Scope* scope() const  { return scope_; }
 
   Handle<String> name() const  { return name_; }
   Mode mode() const  { return mode_; }
@@ skipping 28 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_; }
-  Slot* slot() const;
 
   StaticType* type() { return &type_; }
 
  private:
   Scope* scope_;
   Handle<String> name_;
   Mode mode_;
   bool is_valid_LHS_;
   Kind kind_;
 
@@ skipping 10 matching lines @@
   // rewrite_ is usually a Slot or a Property, but may be any expression.
   Expression* rewrite_;
 
   friend class Scope;  // Has explicit access to rewrite_.
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_VARIABLES_H_