Bug 1758107 - Fix some ESLint no-unused-vars warnings in dom/push/test. r=mt

Differential Revision: https://phabricator.services.mozilla.com/D140324

dom/push/test/xpcshell/test_quota_with_notification.js

@@ -4,7 +4,6 @@
 "use strict";
 
 const userAgentID = "aaabf1f8-2f68-44f1-a920-b88e9e7d7559";
-const nsIPushQuotaManager = Ci.nsIPushQuotaManager;
 
 function run_test() {
   do_get_profile();

dom/push/test/xpcshell/test_register_flush.js

@@ -4,7 +4,6 @@
 "use strict";
 
 const userAgentID = "9ce1e6d3-7bdb-4fe9-90a5-def1d64716f1";
-const channelID = "c26892c5-6e08-4c16-9f0c-0044697b4d85";
 
 function run_test() {
   do_get_profile();

dom/push/test/xpcshell/test_updateRecordNoEncryptionKeys_http2.js

@@ -7,10 +7,6 @@ const { HttpServer } = ChromeUtils.import("resource://testing-common/httpd.js");
 
 var httpServer = null;
 
-XPCOMUtils.defineLazyGetter(this, "serverPort", function() {
-  return httpServer.identity.primaryPort;
-});
-
 function listenHandler(metadata, response) {
   Assert.ok(true, "Start listening");
   httpServer.stop(do_test_finished);