Display a meaningfull error message when trying to capture a stack trace to a proxy.

test/mjsunit/regress/regress-crbug-599067.js

Index: test/mjsunit/regress/regress-crbug-599067.js
diff --git a/test/mjsunit/es6/tail-call-megatest-shard0.js b/test/mjsunit/regress/regress-crbug-599067.js
similarity index 53%
copy from test/mjsunit/es6/tail-call-megatest-shard0.js
copy to test/mjsunit/regress/regress-crbug-599067.js
index 87fe29e136257c9f4cbfd6550ab713f7f644df84..bc10aa44c2f157c22183263e9602747a3482084b 100644
--- a/test/mjsunit/es6/tail-call-megatest-shard0.js
+++ b/test/mjsunit/regress/regress-crbug-599067.js
@@ -2,12 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --harmony-tailcalls
-
 try {
-  load("mjsunit/es6/tail-call-megatest.js");
+  var o = {};
+  var p = new Proxy({}, o);
+  Error.captureStackTrace(p);
 } catch(e) {
-  load("test/mjsunit/es6/tail-call-megatest.js");
+  assertEquals("Cannot pass private property name to proxy trap", e.message);
 }
-
-run_tests(0);