Cleanup blink-side PlzNavigate logic

third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-explicit-domain-isolated-world.html

Index: third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-explicit-domain-isolated-world.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-explicit-domain-isolated-world.html b/third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-explicit-domain-isolated-world.html
index ed1fbd3595d2161963871055b4d2edd15e087eb7..c4d27d989a8d4fdb59e077de2df46863ea28a734 100644
--- a/third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-explicit-domain-isolated-world.html
+++ b/third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-explicit-domain-isolated-world.html
@@ -25,11 +25,13 @@ if (document.location.hostname == '127.0.0.1') {
             }
         });
 
-        testRunner.setIsolatedWorldSecurityOrigin(2, 'chrome-extension://123');
-        var iframe = document.getElementsByTagName('iframe')[0];
-        iframe.focus();
-        document.domain = 'example.test';
-        iframe.src = 'http://subdomain.example.test:8000/security/resources/cross-frame-iframe-for-parent-isolated-world.html';
+        window.onload = function() {
+          testRunner.setIsolatedWorldSecurityOrigin(2, 'chrome-extension://123');
+          var iframe = document.getElementsByTagName('iframe')[0];
+          iframe.focus();
+          document.domain = 'example.test';
+          iframe.src = 'http://subdomain.example.test:8000/security/resources/cross-frame-iframe-for-parent-isolated-world.html';
+        }
     } else {
         testFailed('Test depends on LayoutTestController and must be run by DRT');
     }