Clean up some messiness in Scopes.

src/rewriter.cc

 // 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 507 matching lines @@
       node->right()->set_no_negative_zero(true);
       break;
     case Token::MUL: {
       VariableProxy* lvar_proxy = node->left()->AsVariableProxy();
       VariableProxy* rvar_proxy = node->right()->AsVariableProxy();
       if (lvar_proxy != NULL && rvar_proxy != NULL) {
         Variable* lvar = lvar_proxy->AsVariable();
         Variable* rvar = rvar_proxy->AsVariable();
         if (lvar != NULL && rvar != NULL) {
           if (lvar->mode() == Variable::VAR && rvar->mode() == Variable::VAR) {
-            Slot* lslot = lvar->slot();
-            Slot* rslot = rvar->slot();
+            Slot* lslot = lvar->AsSlot();
+            Slot* rslot = rvar->AsSlot();
             if (lslot->type() == rslot->type() &&
                 (lslot->type() == Slot::PARAMETER ||
                  lslot->type() == Slot::LOCAL) &&
                 lslot->index() == rslot->index()) {
               // A number squared doesn't give negative zero.
               node->set_no_negative_zero(true);
             }
           }
         }
       }
@@ skipping 473 matching lines @@
     optimizer.Optimize(body);
     if (optimizer.HasStackOverflow()) {
       return false;
     }
   }
   return true;
 }
 
 
 } }  // namespace v8::internal