Expect JSReceiver in Runtime_DeleteLookupSlot, not just JSObject.

test/mjsunit/regress/regress-583260.js

Index: test/mjsunit/regress/regress-583260.js
diff --git a/test/mjsunit/compiler/regress-572409.js b/test/mjsunit/regress/regress-583260.js
similarity index 53%
copy from test/mjsunit/compiler/regress-572409.js
copy to test/mjsunit/regress/regress-583260.js
index 126b622625ad4455b4bd2e309ee10e32eb02989e..b0c01f6e9db019a87e07654dfe3b637c8c7bbd2f 100644
--- a/test/mjsunit/compiler/regress-572409.js
+++ b/test/mjsunit/regress/regress-583260.js
@@ -2,9 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-var o = function() {};
-function f() {
-  var lit = { __proto__: o  };
-  o instanceof RegExp;
+__v_1 = {
+  has() { return true }
+};
+__v_2 = new Proxy({}, __v_1);
+function __f_5(object) {
+  with (object) { return delete __v_3; }
 }
-f();
+ __f_5(__v_2)