Error.captureStackTrace should define "stack" property as configurable.

R=verwaest@chromium.org
BUG=393988
LOG=N

Review URL: https://codereview.chromium.org/396063008

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22420 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/messages.js

@@ -1144,7 +1144,8 @@ var StackTraceSetter = function(v) {
 var captureStackTrace = function captureStackTrace(obj, cons_opt) {
   // Define accessors first, as this may fail and throw.
   ObjectDefineProperty(obj, 'stack', { get: StackTraceGetter,
-                                       set: StackTraceSetter});
+                                       set: StackTraceSetter,
+                                       configurable: true });
   %CollectStackTrace(obj, cons_opt ? cons_opt : captureStackTrace);
 }
 

test/mjsunit/regress/regress-crbug-393988.js

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var o = {};
+Error.captureStackTrace(o);
+Object.defineProperty(o, "stack", { value: 1 });
+assertEquals(1, o.stack);