diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/extensions/regress-255245.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/extensions/regress-255245.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 255245;
+var summary = 'Function.prototype.toSource/.toString show "setrval" instead of "return"';
+var actual = '';
+var expect = '';
+
+printBugNumber(BUGNUMBER);
+printStatus (summary);
+
+function f() {
+  try {
+  } catch (e) {
+    return false;
+  }
+  finally {
+  }
+}
+
+if (typeof f.toSource != 'undefined')
+{
+  expect = -1;
+  actual = f.toSource().indexOf('setrval');
+
+  reportCompare(expect, actual, summary);
+}