Add window access checks for Suborigins

LayoutTests/http/tests/security/suborigins/suborigin-blocked-not-in-suborigin-to-suborigin.php

Index: LayoutTests/http/tests/security/suborigins/suborigin-blocked-not-in-suborigin-to-suborigin.php
diff --git a/LayoutTests/http/tests/security/suborigins/suborigin-blocked-not-in-suborigin-to-suborigin.php b/LayoutTests/http/tests/security/suborigins/suborigin-blocked-not-in-suborigin-to-suborigin.php
index 1523b08ef05895ae660ee58b3d08a8932b12c17f..8eab860745652291c736e971dc2f2a5082253d6b 100644
--- a/LayoutTests/http/tests/security/suborigins/suborigin-blocked-not-in-suborigin-to-suborigin.php
+++ b/LayoutTests/http/tests/security/suborigins/suborigin-blocked-not-in-suborigin-to-suborigin.php
@@ -6,18 +6,10 @@
 <script src="/resources/testharnessreport.js"></script>
 </head>
 <script>
-window.onmessage = function() {
-    var iframe = document.getElementById('iframe');
-    var secret = '';
-    try {
-        secret = iframe.contentWindow.secret;
-        assert_unreached();
-        done();
-    } catch(e) {
-        assert_equals(secret, "", "The parent frame should not be able to get the secret value from the child iframe.");
-        done();
-    };
+window.onmessage = function (event) {
+    assert_equals(event.data, 'SecurityError: Blocked a frame with origin \"http://127.0.0.1:8000\" from accessing a cross-origin frame.');
+    done();
 };
 </script>
-<iframe id="iframe" src="resources/childsuborigin.php?suborigin=foobar"></iframe>
+<iframe src="resources/reach-into-iframe.php?childsuborigin=foobar"></iframe>
 </html>