ServiceWorker: Remove Clients.getAll()

LayoutTests/http/tests/serviceworker/resources/postmessage-msgport-to-client-worker.js

 self.onmessage = function(e) {
-  self.clients.getAll().then(function(clients) {
+  self.clients.matchAll().then(function(clients) {
       clients.forEach(function(client) {
           var messageChannel = new MessageChannel();
           messageChannel.port1.onmessage =
             onMessageViaMessagePort.bind(null, client);
           client.postMessage({port: messageChannel.port2},
                              [messageChannel.port2]);
         });
     });
 };
 
 function onMessageViaMessagePort(client, e) {
   var message = e.data;
   if ('value' in message) {
     client.postMessage({ack: 'Acking value: ' + message.value});
   } else if ('done' in message) {
     client.postMessage({done: true});
   }
 }