scheduler: Re-enable timer throttling for hidden frames

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/test-helpers.js

 // Adapter for testharness.js-style tests with Service Workers
 
 function service_worker_unregister_and_register(test, url, scope) {
   if (!scope || scope.length == 0)
     return Promise.reject(new Error('tests must define a scope'));
 
   var options = { scope: scope };
   return service_worker_unregister(test, scope)
     .then(function() {
         return navigator.serviceWorker.register(url, options);
@@ skipping 33 matching lines @@
 }
 
 // Adds an iframe to the document and returns a promise that resolves to the
 // iframe when it finishes loading. When |options.auto_remove| is set to
 // |false|, the caller is responsible for removing the iframe
 // later. Otherwise, the frame will be removed after all tests are finished.
 function with_iframe(url, options) {
   return new Promise(function(resolve) {
       var frame = document.createElement('iframe');
       frame.src = url;
+      // Make sure the iframe stays in the viewport even if the test creates
+      // many of them. Otherwise some iframes may end up being throttled.
+      frame.style.position = 'absolute';
       frame.onload = function() { resolve(frame); };
       document.body.appendChild(frame);
       if (typeof options === 'undefined')
         options = {};
       if (typeof options.auto_remove === 'undefined')
         options.auto_remove = true;
       if (options.auto_remove)
         add_completion_callback(function() { frame.remove(); });
     });
 }
@@ skipping 135 matching lines @@
 
 function login(test, local, remote) {
   var suffix = (local.indexOf("https") != -1) ? "s": "";
   return test_login(test, local, 'username1' + suffix, 'password1' + suffix,
                     'cookie1')
     .then(function() {
         return test_login(test, remote, 'username2' + suffix,
                           'password2' + suffix, 'cookie2');
       });
 }