Fix cluster-fuzz found regression with d8 Workers

test/mjsunit/regress/regress-crbug-506549.js

Index: test/mjsunit/regress/regress-crbug-506549.js
diff --git a/test/mjsunit/regress/regress-crbug-506549.js b/test/mjsunit/regress/regress-crbug-506549.js
new file mode 100644
index 0000000000000000000000000000000000000000..40e162caf5ef4a18ed21e412e0771cab38ad12c3
--- /dev/null
+++ b/test/mjsunit/regress/regress-crbug-506549.js
@@ -0,0 +1,10 @@
+// Copyright 2015 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.
+
+if (this.Worker) {
+  var __v_5 = {};
+  __v_5.__defineGetter__('byteLength', function() {foo();});
+  var __v_8 = new Worker('onmessage = function() {};');
+  assertThrows(function() { __v_8.postMessage(__v_5); });
+}