Update UnloadReference to use new virtual frame.

src/codegen-ia32.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 526 matching lines @@
     // Anything else is a runtime error.
     LoadAndSpill(e);
     frame_->CallRuntime(Runtime::kThrowReferenceError, 1);
   }
 }
 
 
 void CodeGenerator::UnloadReference(Reference* ref) {
   // Pop a reference from the stack while preserving TOS.
   Comment cmnt(masm_, "[ UnloadReference");
+  Result top(this);
   int size = ref->size();
   if (size == 1) {
-    frame_->EmitPop(eax);
-    __ mov(frame_->Top(), eax);
+    top = frame_->Pop();
+    // Replace Drop(), Push() sequence with ReplaceTop().
+    frame_->Drop();
+    frame_->Push(&top);
   } else if (size > 1) {
-    frame_->EmitPop(eax);
+    top = frame_->Pop();
     frame_->Drop(size);
-    frame_->EmitPush(eax);
+    frame_->Push(&top);
   }
 }
 
 
 class ToBooleanStub: public CodeStub {
  public:
   ToBooleanStub() { }
 
   void Generate(MacroAssembler* masm);
 
@@ skipping 5200 matching lines @@
 
   // Slow-case: Go through the JavaScript implementation.
   __ bind(&slow);
   __ InvokeBuiltin(Builtins::INSTANCE_OF, JUMP_FUNCTION);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal