Fix wrapping of receiver for non-strict callbacks.

test/mjsunit/getter-in-value-prototype.js

 // Copyright 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 13 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Test that getters can be defined and called on value prototypes.
 //
 // This used to fail because of an invalid cast of the receiver to a
 // JSObject.
 
 String.prototype.__defineGetter__('x', function() { return this; });
-assertEquals('asdf', 'asdf'.x);
+assertEquals(Object('asdf'), 'asdf'.x);