Remove variable rewrites and the unneccesary Slot class.

test/mjsunit/compiler/delete.js

-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2011 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
 //       with the distribution.
@@ skipping 47 matching lines @@
 // expected in accumulator.
 assertEquals(2, (function (x) { return (delete x) || 2; })(0));
 // In a hybrid value/test context, expression is always true, value
 // expected on stack.
 assertEquals(2, ((delete 0) || 2) + 1);
 // In a hybrid value/test context, expression is always false, value
 // expected on stack.
 assertEquals(3, (function (x) { return ((delete x) || 2) + 1; })(0));
 
 
-// 'this' at toplevel is different from all other global variables---not
-// deletable.
+// 'this' is not a Reference so delete returns true (see section 11.4.1,
+// step 2 of ES 5.1).
 assertEquals(true, delete this);
+assertEquals(true, (function () { return delete this; })());