diff --git a/js/tests/e4x/extensions/regress-462734-01.js b/js/tests/e4x/extensions/regress-462734-01.js
new file mode 100644
index 000000000000..3505e6adfa80
--- /dev/null
+++ b/js/tests/e4x/extensions/regress-462734-01.js
@@ -0,0 +1,67 @@
+/* -*- Mode: java; tab-width:8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is JavaScript Engine testing utilities.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s): Gary Kwong
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+gTestfile = 'regress-462734-01.js';
+
+var summary = 'Do not assert: pobj_ == obj2';
+var BUGNUMBER = 462734;
+var actual = '';
+var expect = '';
+
+printBugNumber(BUGNUMBER);
+START(summary);
+
+var save__proto__ = this.__proto__;
+
+try
+{
+    for (x in function(){}) (<x><y/></x>);
+    this.__defineGetter__("x", Function);
+    __proto__ = x;
+    prototype += <x><y/></x>;
+}
+catch(ex)
+{
+    print(ex + '');
+}
+
+__proto__ = save__proto__;
+
+TEST(1, expect, actual);
+
+END();
diff --git a/js/tests/ecma_3/Statements/12.10-01.js b/js/tests/ecma_3/Statements/12.10-01.js
new file mode 100644
index 000000000000..af5f0842559d
--- /dev/null
+++ b/js/tests/ecma_3/Statements/12.10-01.js
@@ -0,0 +1,68 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is JavaScript Engine testing utilities.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s): Brendan Eich
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+var gTestfile = '12.10-01.js';
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 462734;
+var summary = 'evaluating lhs "Reference" *before* evaluating rhs';
+var actual = '';
+var expect = '';
+
+
+//-----------------------------------------------------------------------------
+test();
+//-----------------------------------------------------------------------------
+
+function test()
+{
+  enterFunc ('test');
+  printBugNumber(BUGNUMBER);
+  printStatus (summary);
+
+  var x = 1;
+  var o = {};
+  with (o)
+    x = o.x = 2;
+  print(x);
+
+  expect = 4;
+  actual = x + o.x;
+
+  reportCompare(expect, actual, summary);
+
+  exitFunc ('test');
+}
diff --git a/js/tests/js1_5/extensions/regress-462734-02.js b/js/tests/js1_5/extensions/regress-462734-02.js
new file mode 100644
index 000000000000..03223a9b636d
--- /dev/null
+++ b/js/tests/js1_5/extensions/regress-462734-02.js
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is JavaScript Engine testing utilities.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s): Gary Kwong
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+var gTestfile = 'regress-462734-02.js';
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 462734;
+var summary = 'Do not assert: pobj_ == obj2';
+var actual = '';
+var expect = '';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+var save__proto__ = __proto__;
+
+try
+{
+  for (x in function(){}) ([]);
+  this.__defineGetter__("x", Function);
+  __proto__ = x;
+  prototype += [];
+}
+catch(ex)
+{
+  print(ex + '');
+}
+
+__proto__ = save__proto__;
+
+reportCompare(expect, actual, summary);
diff --git a/js/tests/js1_5/extensions/regress-462734-03.js b/js/tests/js1_5/extensions/regress-462734-03.js
new file mode 100644
index 000000000000..78eafe0b81df
--- /dev/null
+++ b/js/tests/js1_5/extensions/regress-462734-03.js
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is JavaScript Engine testing utilities.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s): Igor Bukanov
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+var gTestfile = 'regress-462734-03.js';
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 462734;
+var summary = 'Do not assert: pobj_ == obj2';
+var actual = '';
+var expect = '';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+var save__proto__ = __proto__;
+
+try
+{
+  Function.prototype.prototype;
+  __proto__ = Function();
+  prototype = prototype;
+}
+catch(ex)
+{
+  print(ex + '');
+}
+
+__proto__ = save__proto__;
+
+reportCompare(expect, actual, summary);
diff --git a/js/tests/js1_5/extensions/regress-462734-04.js b/js/tests/js1_5/extensions/regress-462734-04.js
new file mode 100644
index 000000000000..9b37a65de7f7
--- /dev/null
+++ b/js/tests/js1_5/extensions/regress-462734-04.js
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is JavaScript Engine testing utilities.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2008
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s): Igor Bukanov
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+var gTestfile = 'regress-462734-04.js';
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 462734;
+var summary = 'Do not assert: pobj_ == obj2';
+var actual = '';
+var expect = '';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+var save__proto__ = __proto__;
+
+try
+{
+  Function.prototype.prototype = function() { return 42; }
+  __proto__ = Function();
+  prototype = prototype;
+}
+catch(ex)
+{
+  print(ex + '');
+}
+
+expect = 'object';
+actual = typeof prototype;
+
+__proto__ = save__proto__;
+
+reportCompare(expect, actual, summary);