ServiceWorker: add ServiceWorkerClients.claim() support (3/3).

LayoutTests/http/tests/serviceworker/resources/interfaces-worker.js

 importScripts('interfaces.js');
 importScripts('worker-testharness.js');
 importScripts('/resources/testharness-helpers.js');
 
 var EVENT_HANDLER = 'object';
 
 test(function() {
     verify_interface('ServiceWorkerGlobalScope',
                      self,
                      {
                        clients: 'object',
                        close: 'function',
                        registration: 'object',
                        skipWaiting: 'function',
 
                        onactivate: EVENT_HANDLER,
                        onfetch: EVENT_HANDLER,
                        oninstall: EVENT_HANDLER,
                        onmessage: EVENT_HANDLER
                      });
   }, 'ServiceWorkerGlobalScope');
 
 test(function() {
     verify_interface('Clients',
                      self.clients,
                      {
+                       claim: 'function',
                        getAll: 'function'
                      });
   }, 'Clients');
 
 test(function() {
     verify_interface('Client');
     // FIXME: Get an instance and test it, or ensure property exists on
     // prototype.
   }, 'Client');
 
@@ skipping 34 matching lines @@
 
 test(function() {
     assert_equals(new ExtendableEvent('ExtendableEvent').type, 'ExtendableEvent');
     assert_equals(new InstallEvent('InstallEvent').type, 'InstallEvent');
 
     assert_equals(new InstallEvent('InstallEvent').cancelable, false);
     assert_equals(new InstallEvent('InstallEvent').bubbles, false);
     assert_equals(new InstallEvent('InstallEvent', { cancelable : true }).cancelable, true);
     assert_equals(new InstallEvent('InstallEvent', { bubbles : true }).bubbles, true);
   }, 'Event constructors');