Cleanup blink-side PlzNavigate logic

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

Index: third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-isolated-world.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-isolated-world.html b/third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-isolated-world.html
index 1235b6a483d2c27867adf4c92eecac735f08020a..8b8ec86d7c4b671befa70b25460fcfd82b73b5ed 100644
--- a/third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-isolated-world.html
+++ b/third_party/WebKit/LayoutTests/http/tests/security/cross-frame-access-parent-isolated-world.html
@@ -22,10 +22,12 @@ if (window.testRunner) {
         }
     });
 
-    testRunner.setIsolatedWorldSecurityOrigin(2, 'chrome-extension://123');
-    var iframe = document.getElementsByTagName('iframe')[0];
-    iframe.focus();
-    iframe.src = 'http://127.0.0.1:8080/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();
+      iframe.src = 'http://127.0.0.1:8080/security/resources/cross-frame-iframe-for-parent-isolated-world.html';
+    }
 } else {
     testFailed('Test depends on LayoutTestController and must be run by DRT');
 }