Reflect recent spec changes to V8 Extra ReadableStream impl

third_party/WebKit/LayoutTests/http/tests/streams/resources/test-utils.js

 'use strict';
 
 self.getterRejects = (t, obj, getterName, target) => {
   const getter = Object.getOwnPropertyDescriptor(obj, getterName).get;
 
   return promise_rejects(t, new TypeError(), getter.call(target));
 };
 
 self.methodRejects = (t, obj, methodName, target) => {
   const method = obj[methodName];
@@ skipping 22 matching lines @@
     // Present in some WebKit development environments
     GCController.collect();
   } else {
     /* eslint-disable no-console */
     console.warn('Tests are running without the ability to do manual garbage collection. They will still work, but ' +
       'coverage will be suboptimal.');
     /* eslint-enable no-console */
   }
 };
 
-self.delay = ms => new Promise(resolve => setTimeout(resolve, ms));
+self.delay = ms => new Promise(resolve => step_timeout(resolve, ms));