[ServiceWorker] Fix bugs of wpt tests for Client.navigate

third_party/WebKit/LayoutTests/resources/testharness.js

 /*global self*/
 /*jshint latedef: nofunc*/
 /*
 Distributed under both the W3C Test Suite License [1] and the W3C
 3-clause BSD License [2]. To contribute to a W3C Test Suite, see the
 policies and contribution forms [3].
 
 [1] http://www.w3.org/Consortium/Legal/2008/04-testsuite-license
 [2] http://www.w3.org/Consortium/Legal/2008/03-bsd-license
 [3] http://www.w3.org/2004/10/27-testcases
@@ skipping 465 matching lines @@
         throw new Error("Unsupported test environment");
     }
 
     var test_environment = create_test_environment();
 
     function is_shared_worker(worker) {
         return 'SharedWorker' in self && worker instanceof SharedWorker;
     }
 
     function is_service_worker(worker) {
-        return 'ServiceWorker' in self && worker instanceof ServiceWorker;
+        // The worker object may be from another execution context,
+        // so do not use instanceof here.
+        return 'ServiceWorker' in self &&
+            Object.prototype.toString.call(worker) == '[object ServiceWorker]';
     }
 
     /*
      * API functions
      */
 
     function test(func, name, properties)
     {
         var test_name = name ? name : test_environment.next_default_test_name();
         properties = properties ? properties : {};
@@ skipping 2292 matching lines @@
         done();
     };
 
     addEventListener("error", error_handler, false);
     addEventListener("unhandledrejection", function(e){ error_handler(e.reason); }, false);
 
     test_environment.on_tests_ready();
 
 })();
 // vim: set expandtab shiftwidth=4 tabstop=4: