[turbofan] Fix exception message for non-constructables.

test/message/call-non-constructable.js

+// Copyright 2016 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.
+
+// Note that {unescape} is an example of a non-constructable function. If that
+// ever changes and this test needs to be adapted, make sure to choose another
+// non-constructable {JSFunction} object instead.
+new unescape();