Import w3c tests for the service workers

third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/extendable-event-async-waituntil.js

 var result = 'FAIL: did not throw.';
 
 self.addEventListener('message', function(event) {
     event.data.port.postMessage(result);
   });
 
 self.addEventListener('install', function(event) {
     self.installEvent = event;
   });
 
 self.addEventListener('activate', function(event) {
     try {
       self.installEvent.waitUntil(new Promise(function(){}));
     } catch (error) {
       if (error.name == 'InvalidStateError')
         result = 'PASS';
       else
         result = 'FAIL: unexpected exception: ' + error;
     }
   });